Science.gov

Sample records for afterglow

  1. Afterglow Complex Plasma

    SciTech Connect

    Samarian, A. A.; Boufendi, L.; Mikikian, M.

    2008-09-07

    The review of the first detailed experimental and theoretical studies of complex plasma in RF discharge afterglow is presented. The studies have been done in a frame of FAST collaborative research project between Complex Plasma Laboratory of the University of Sydney and the GREMI laboratory of Universite d'Orleans. We examined the existing models of plasma decay, presents experimental observations of dust dynamics under different afterglow complex plasma conditions, presents the experimental data obtained (in particular the presence of positively charged particles in discharge afterglow), discusses the use of dust particles as a probe to study the diffusion losses in afterglow plasmas.

  2. Methodology in the Afterglow

    ERIC Educational Resources Information Center

    Hofsess, Brooke Anne

    2013-01-01

    My dissertation study seeks to understand how artist-teacher renewal may be nurtured through aesthetic experiential play in a Masters of Art Education degree program, and beyond, as my former students/participants and myself experience finding ourselves in its afterglow. "Aesthetic experiential play" could be described as a playful,…

  3. The air afterglow revisited

    NASA Technical Reports Server (NTRS)

    Kaufman, F.

    1972-01-01

    The air afterglow, 0 + NO2 chemiluminescence, is discussed in terms of fluorescence, photodissociation, and quantum theoretical calculations of NO2. The experimental results presented include pressure dependence, M-dependence, spectral dependence of P and M, temperature dependence, and infrared measurements. The NO2 energy transfer model is also discussed.

  4. Chameleon induced atomic afterglow

    SciTech Connect

    Brax, Philippe; Burrage, Clare

    2010-11-01

    The chameleon is a scalar field whose mass depends on the density of its environment. Chameleons are necessarily coupled to matter particles and will excite transitions between atomic energy levels in an analogous manner to photons. When created inside an optical cavity by passing a laser beam through a constant magnetic field, chameleons are trapped between the cavity walls and form a standing wave. This effect will lead to an afterglow phenomenon even when the laser beam and the magnetic field have been turned off, and could be used to probe the interactions of the chameleon field with matter.

  5. On the anomalous afterglow seen in a chameleon afterglow search

    SciTech Connect

    Steffen, Jason H.; Baumbaugh, Alan; Chou, Aaron S.; Tomlin, Ray; Upadhye, Amol; /Argonne, PHY

    2012-05-01

    We present data from our investigation of the anomalous orange-colored afterglow that was seen in the GammeV Chameleon Afterglow Search (CHASE). These data include information about the broadband color of the observed glow, the relationship between the glow and the temperature of the apparatus, and other data taken prior to, and during the science operations of CHASE. While differing in several details, the generic properties of the afterglow from CHASE are similar to luminescence seen in some vacuum compounds. Contamination from this, or similar, luminescent signatures will likely impact the design of implementation of future experiments involving single photon detectors and high intensity light sources in a cryogenic environment.

  6. Short GRB Prompt and Afterglow Correlations

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2007-01-01

    The Swift data set on short GRBs has now grown large enough to study correlations of key parameters. The goal is to compare long and short bursts to better understand similarities and differences in the burst origins. In this study we consider the both prompt and afterglow fluxes. It is found that the optical, X-ray and gamma-ray emissions are linearly correlated - stronger bursts tend to have brighter afterglows, and bursts with brighter X-ray afterglow tend to have brighter optical afterglow. Both the prompt and afterglow fluxes are, on average, lower for short bursts than for long. Although there are short GRBs with undetected optical emission, there is no evidence for "dark" short bursts with anomalously low opt/X ratios. The weakest short bursts have a low X-ray/gamma-ray ratio.

  7. GLAST Prospects for Swift-Era Afterglows

    SciTech Connect

    Gou, L.J.; Meszaros, P.; /Penn State U.

    2011-11-23

    We calculate the GeV spectra of gamma-ray burst afterglows produced by inverse Compton scattering of these objects sub-MeV emission. We improve on earlier treatments by using refined afterglow parameters and new model developments motivated by recent Swift observations. We present time-dependent GeV spectra for standard, constant-parameter models, as well as for models with energy injection and with time-varying parameters, for a range of burst parameters. We evaluate the limiting redshift to which such afterglows can be detected by the GLAST Large Area Telescope, as well as by AGILE.

  8. Dust Cloud Dynamics in Complex Plasma Afterglow

    SciTech Connect

    Layden, B.; Samarian, A. A.; Vladimirov, S. V.; Coueedel, L.

    2008-09-07

    Experimental observations of dust cloud dynamics in a RF discharge afterglow are presented. Image analysis is used to extract information from videos taken of the plasma. Estimations of the mean confining electric field have been made for different experimental conditions using a model for the contraction of the dust cloud. Dust particle trajectories in the late afterglow evidence the co-existence of positively and negatively charged dust particles.

  9. GRB afterglows in the nonrelativistic phase

    NASA Astrophysics Data System (ADS)

    Huang, Y. F.; Lu, T.

    2008-10-01

    When discussing the afterglows of gamma-ray bursts analytically, it is usually assumed that the external shock is always ultra-relativisitc, with the bulk Lorentz factor much larger than 1. However, we show that the deceleration of the external shock is actually very quick. The afterglow may typically enter the nonrelativistic phase in several days to teens of days, and may even enter the deep Newtonian phase in tens of days to several months. One thus should be careful in using those familiar analytical expressions that are derived only under the ultra-relativistic assumption. To explain the observed afterglows that typically last for a few weeks to several months, we need to consider the dynamics and radiation in the nonrelativisitic phase.

  10. GRB Off-Axis Afterglows and the Emission from the Accompanying Supernovae

    NASA Astrophysics Data System (ADS)

    Kathirgamaraju, A. K.; Duran, R. B. D.; Giannios, D. G.

    2016-10-01

    I will discuss the prospect of detecting orphan afterglows with upcoming radio surveys. Using simulations generated by the Afterglow Library and using data from 75 GRB afterglows. We also discuss how emission from SNe and other components affect our results.

  11. The Swift XRT: Observations of Early X-ray Afterglows

    SciTech Connect

    Burrows, David N.; Kennea, J. A.; Nousek, J. A.; Osborne, J. P.; O'Brien, P. T.; Chincarini, G.; Tagliaferri, G.; Giommi, P.; Zhang, B.

    2006-05-19

    During the first year of operations of the Swift observatory, the X-ray Telescope has made a number of discoveries concerning the nature of X-ray afterglows of both long and short GRBs. We highlight the key findings, which include rapid declines at early times, a standard template of afterglow light curve shapes, common flaring, and the discovery of the first short GRB afterglow.

  12. Study of argon-oxygen flowing afterglow

    NASA Astrophysics Data System (ADS)

    Mazánková, V.; Trunec, D.; Navrátil, Z.; Raud, J.; Krčma, F.

    2016-06-01

    The reaction kinetics in argon-oxygen flowing afterglow (post-discharge) was studied using NO titration and optical emission spectroscopy. The flowing DC post-discharge in argon-oxygen mixture was created in a quartz tube at the total gas pressure of 1000 Pa and discharge power of 90 W. The O(3P) atom concentration was determined by NO titration at different places along the flow tube. The optical emission spectra were also measured along the flow tube. Argon spectral lines, oxygen lines at 777 nm and 844.6 nm and atmospheric A-band of {{\\text{O}}2} were identified in the spectra. Rotational temperature of {{\\text{O}}2} was determined from the oxygen atmospheric A-band and also the outer wall temperature of the flow tube was measured by a thermocouple and by an IR thermometer. A zero-dimensional kinetic model for the reactions in the afterglow was developed. This model allows the time dependencies of particle concentrations and of gas temperature to be calculated. The wall recombination probability for O(3P) atoms {γ\\text{O≤ft(\\text{P}\\right)}}=≤ft(1.63+/- 0.06\\right)× {{10}-3} and wall deactivation probability for {{\\text{O}}2} (b {{}1}Σ\\text{g}+ ) molecules {γ{{\\text{O}2}≤ft(\\text{b}\\right)}}=≤ft(1.7+/- 0.1\\right)× {{10}-3} were determined from the fit of model results to experimental data. Sensitivity analysis was applied for the analysis of kinetic model in order to reveal the most important reactions in the model. The calculated gas temperature increases in the afterglow and then decreases at later afterglow times after reaching the maximum. This behavior is in good agreement with the spatial rotational temperature dependence. A similar trend was also observed at outer wall temperature measurement.

  13. Gamma ray burst outflows and afterglows

    NASA Astrophysics Data System (ADS)

    Morsony, Brian J.

    2008-08-01

    We carry out a theoretical investigation of jet propagation in Gamma Ray Bursts and examine the jitter radiation mechanism as a means of producing prompt and afterglow emission. We study the long-term evolution of relativistic jets in collapsars and examine the effects of viewing angle on the subsequent gamma ray bursts. Our simulations allow us to single out three phases in the jet evolution: a precursor phase in which relativistic material turbulently shed from the head of the jet first emerges from the star; a shocked jet phase where a fully shocked jet of material is emerging; and an unshocked jet phase where the jet consists of a free-streaming, unshocked core surrounded by a thin boundary layer of shocked jet material. We also carry out a series of simulations with central engines that vary on long time periods comparable to the breakout time of the jet, on short time periods (0.1s) much less than the breakout time, and finally that decay as a power law at late times. We conclude that rapid variability seen in prompt GRB emission, as well as shallow decays and flares seen in the X-ray afterglow, can be caused by central engine variability. Finally, we present a detailed computation of the jitter radiation spectrum, including self-absorption, for electrons inside Weibel-like shock- generated magnetic fields. We apply our results to the case of the prompt and afterglow emission of gamma-ray bursts. We conclude that jitter and synchrotron afterglows can be distinguished from each other with good quality observations. However, it is unlikely that the difference can explain the peculiar behavior of several recent observations, such as flat X-ray slopes and uncorrelated optical and X-ray behavior.

  14. Rapid GRB Afterglow Response With SARA

    NASA Astrophysics Data System (ADS)

    Garimella, K. V.; Homewood, A. L.; Hartmann, D. H.; Riddle, C.; Fuller, S.; Manning, A.; McIntyre, T.; Henson, G.

    2006-05-01

    The Clemson GRB Follow-Up program utilizes the SARA 0.9-m telescope to observe optical afterglows of Gamma Ray Bursts. SARA is not yet robotic; it operates under direct and Target-of-Opportunity (ToO) interrupt modes. To facilitate rapid response and timely reporting of data analysis results, we developed a software suite that operates in two phases: first, to notify observers of a burst and assist in data collection, and second, to quickly analyze the images.

  15. Afterglows from precursors in gamma-ray bursts. Application to the optical afterglow of GRB 091024

    NASA Astrophysics Data System (ADS)

    Nappo, F.; Ghisellini, G.; Ghirlanda, G.; Melandri, A.; Nava, L.; Burlon, D.

    2014-12-01

    About 15 per cent of gamma-ray bursts have precursors, i.e. emission episodes preceding the main event, whose spectral and temporal properties are similar to the main emission. We propose that precursors have their own fireball, producing afterglow emission due to the dissipation of the kinetic energy via external shock. In the time lapse between the precursor and the main event, we assume that the central engine is not completely turned off, but it continues to eject relativistic material at a smaller rate, whose emission is below the background level. The precursor fireball generates a first afterglow by the interaction with the external circumburst medium. Matter injected by the central engine during the `quasi-quiescent' phase replenishes the external medium with material in relativistic motion. The fireball corresponding to the main prompt emission episode rams into this moving material, producing a second afterglow, and finally catches up and merges with the first precursor fireball. We test this scenario over GRB 091024, an event with a precursor in the prompt light curve and two well-defined bumps in the optical afterglow, obtaining an excellent agreement with the existing data.

  16. Afterglows from the largest explosions in the universe

    PubMed Central

    Hartmann, Dieter H.

    1999-01-01

    The distinction of “largest explosions in the universe” has been bestowed on cosmic gamma-ray bursts. Their afterglows are brighter than supernovae and therefore are called hypernovae. Photometry and spectroscopy of these afterglows have provided major breakthroughs in our understanding of this mysterious phenomenon. PMID:10220364

  17. GRB 090902B: AFTERGLOW OBSERVATIONS AND IMPLICATIONS

    SciTech Connect

    Pandey, S. B.; Akerlof, C.; McKay, T. A.; Swenson, C. A.; Perley, D. A.; Kleiser, I. K. W.; Guidorzi, C.; Wiersema, K.; Malesani, D.; Ashley, M. C. B.; Bersier, D.; Cano, Z.; Kobayashi, S.; Melandri, A.; Mottram, C. J.; Gomboc, A.; Ilyin, I.; Jakobsson, P.; Kouveliotou, C.; Levan, A. J.

    2010-05-01

    The optical-infrared afterglow of the Large Area Telescope (LAT)-detected long-duration burst, GRB 090902B, has been observed by several instruments. The earliest detection by ROTSE-IIIa occurred 80 minutes after detection by the Gamma-ray Burst Monitor instrument on board the Fermi Gamma-Ray Space Telescope, revealing a bright afterglow and a decay slope suggestive of a reverse shock origin. Subsequent optical-IR observations followed the light curve for 6.5 days. The temporal and spectral behavior at optical-infrared frequencies is consistent with synchrotron fireball model predictions; the cooling break lies between optical and XRT frequencies {approx}1.9 days after the burst. The inferred electron energy index is p = 1.8 {+-} 0.2, which would however imply an X-ray decay slope flatter than observed. The XRT and LAT data have similar spectral indices and the observed steeper value of the LAT temporal index is marginally consistent with the predicted temporal decay in the radiative regime of the forward shock model. Absence of a jet break during the first 6 days implies a collimation-corrected {gamma}-ray energy E{sub {gamma}} > 2.2 x 10{sup 52} erg, one of the highest ever seen in a long-duration gamma-ray bursts. More events combining GeV photon emission with multiwavelength observations will be required to constrain the nature of the central engine powering these energetic explosions and to explore the correlations between energetic quanta and afterglow emission.

  18. Afterglow Radiation from Gamma Ray Bursts

    SciTech Connect

    Desmond, Hugh; /Leuven U. /SLAC

    2006-08-28

    Gamma-ray bursts (GRB) are huge fluxes of gamma rays that appear randomly in the sky about once a day. It is now commonly accepted that GRBs are caused by a stellar object shooting off a powerful plasma jet along its rotation axis. After the initial outburst of gamma rays, a lower intensity radiation remains, called the afterglow. Using the data from a hydrodynamical numerical simulation that models the dynamics of the jet, we calculated the expected light curve of the afterglow radiation that would be observed on earth. We calculated the light curve and spectrum and compared them to the light curves and spectra predicted by two analytical models of the expansion of the jet (which are based on the Blandford and McKee solution of a relativistic isotropic expansion; see Sari's model [1] and Granot's model [2]). We found that the light curve did not decay as fast as predicted by Sari; the predictions by Granot were largely corroborated. Some results, however, did not match Granot's predictions, and more research is needed to explain these discrepancies.

  19. MULTI-WAVELENGTH AFTERGLOWS OF FAST RADIO BURSTS

    SciTech Connect

    Yi, Shuang-Xi; Gao, He; Zhang, Bing

    2014-09-01

    The physical origin of fast radio bursts (FRBs) is unknown. Detecting electromagnetic counterparts to FRBs in other wavelengths is essential to measure their distances and to determine their physical origin. Assuming that at least some of them are of cosmological origin, we calculate their afterglow light curves in multiple wavelengths (X-rays, optical, and radio) by assuming a range of total kinetic energies and redshifts. We focus on forward shock emission, but also consider the possibility that some of the FRBs might have bright reverse shock emission. In general, FRB afterglows are too faint to be detected by current detectors. Only if an FRB has a very low radiative efficiency in radio (hence, a very large kinetic energy), and when it is close enough to observe can its afterglow be detected in the optical and radio bands. We discuss observational strategies for detecting these faint afterglows using future telescopes such as Large Synoptic Survey Telescope and Expanded Very Large Array.

  20. Nonlinear Particle Acceleration and Thermal Particles in GRB Afterglows

    NASA Astrophysics Data System (ADS)

    Warren, Donald C.; Ellison, Donald C.; Barkov, Maxim V.; Nagataki, Shigehiro

    2017-02-01

    The standard model for GRB afterglow emission treats the accelerated electron population as a simple power law, N(E)\\propto {E}-p for p≳ 2. However, in standard Fermi shock acceleration, a substantial fraction of the swept-up particles do not enter the acceleration process at all. Additionally, if acceleration is efficient, then the nonlinear back-reaction of accelerated particles on the shock structure modifies the shape of the nonthermal tail of the particle spectra. Both of these modifications to the standard synchrotron afterglow impact the luminosity, spectra, and temporal variation of the afterglow. To examine the effects of including thermal particles and nonlinear particle acceleration on afterglow emission, we follow a hydrodynamical model for an afterglow jet and simulate acceleration at numerous points during the evolution. When thermal particles are included, we find that the electron population is at no time well fitted by a single power law, though the highest-energy electrons are; if the acceleration is efficient, then the power-law region is even smaller. Our model predicts hard–soft–hard spectral evolution at X-ray energies, as well as an uncoupled X-ray and optical light curve. Additionally, we show that including emission from thermal particles has drastic effects (increases by factors of 100 and 30, respectively) on the observed flux at optical and GeV energies. This enhancement of GeV emission makes afterglow detections by future γ-ray observatories, such as CTA, very likely.

  1. The ultra-long GRB 111209A. II. Prompt to afterglow and afterglow properties

    SciTech Connect

    Stratta, G.; Gendre, B.; Boër, M.; Atteia, J. L.; Coward, D. M.; Howell, E.; De Pasquale, M.; Oates, S.; Klotz, A.; Piro, L.

    2013-12-10

    The 'ultra-long' gamma-ray burst GRB 111209A at redshift z = 0.677 is the longest GRB ever observed thus far, with a rest frame prompt emission duration of ∼4 hr. In order to explain the burst exceptional longevity, a low-metallicity blue supergiant progenitor was invoked. In this article we further constrain the phenomenology and progenitor properties of this peculiar GRB by performing a multiband temporal and spectral analysis of both the prompt and the afterglow emission. We use proprietary and publicly available data from Swift, Konus WIND, XMM-Newton, and TAROT, as well as from other ground-based optical and radio telescopes. We find some peculiar properties that are possibly connected to the exceptional nature of this burst, namely: (1) an unprecedented large optical delay of 410 ± 50 s between the peak time in gamma-rays and the peak time in the optical of a marked multiwavelength flare; (2) multiwavelength prompt emission spectral modeling requires a certain amount of dust in the circumburst environment. The dust produces a rest frame visual extinction of A{sub V} = 0.3-1.5 mag, and may undergo destruction at late times; and (3) we detect the presence of a hard spectral extra power-law component at the end of the X-ray steep steep decay phase and before the start of the X-ray afterglow, which has never been revealed thus far in past GRBs. The optical afterglow shows more usual properties; it has a flux power-law decay with an index of 1.6 ± 0.1 and a late rebrightening feature observed at ∼1.1 the day after the first Burst Alert Telescope trigger. We discuss our findings in the context of several possible interpretations that have been given thus far of the complex multiband GRB phenomenology and propose a binary channel formation for the blue supergiant progenitor.

  2. The Ultra-long GRB 111209A. II. Prompt to Afterglow and Afterglow Properties

    NASA Astrophysics Data System (ADS)

    Stratta, G.; Gendre, B.; Atteia, J. L.; Boër, M.; Coward, D. M.; De Pasquale, M.; Howell, E.; Klotz, A.; Oates, S.; Piro, L.

    2013-12-01

    The "ultra-long" gamma-ray burst GRB 111209A at redshift z = 0.677 is the longest GRB ever observed thus far, with a rest frame prompt emission duration of ~4 hr. In order to explain the burst exceptional longevity, a low-metallicity blue supergiant progenitor was invoked. In this article we further constrain the phenomenology and progenitor properties of this peculiar GRB by performing a multiband temporal and spectral analysis of both the prompt and the afterglow emission. We use proprietary and publicly available data from Swift, Konus WIND, XMM-Newton, and TAROT, as well as from other ground-based optical and radio telescopes. We find some peculiar properties that are possibly connected to the exceptional nature of this burst, namely: (1) an unprecedented large optical delay of 410 ± 50 s between the peak time in gamma-rays and the peak time in the optical of a marked multiwavelength flare; (2) multiwavelength prompt emission spectral modeling requires a certain amount of dust in the circumburst environment. The dust produces a rest frame visual extinction of AV = 0.3-1.5 mag, and may undergo destruction at late times; and (3) we detect the presence of a hard spectral extra power-law component at the end of the X-ray steep steep decay phase and before the start of the X-ray afterglow, which has never been revealed thus far in past GRBs. The optical afterglow shows more usual properties; it has a flux power-law decay with an index of 1.6 ± 0.1 and a late rebrightening feature observed at ~1.1 the day after the first Burst Alert Telescope trigger. We discuss our findings in the context of several possible interpretations that have been given thus far of the complex multiband GRB phenomenology and propose a binary channel formation for the blue supergiant progenitor.

  3. Emission spectrum of a sporadic fireball afterglow

    NASA Astrophysics Data System (ADS)

    Madiedo, J.; Trigo-Rodríguez, J.

    2014-07-01

    A mag. -11 fireball was imaged over southern Spain on April 14, 2013 at 22:35:49.8 ± 0.1s UTC. Its emission spectrum was also obtained. This event was assigned the SPMN code 140413 after the recording date. By the end of its atmospheric path, it exhibited a very bright flare which resulted in a persistent train whose spectrum was recorded. Here we present a preliminary analysis of this event and focus special attention on the evolution of the main emission lines in the spectrum of the afterglow. An array of low-lux CCD video devices (models 902H and 902H Ultimate from Watec Co.) operating from our stations at Sevilla and El Arenosillo was employed to record the SPMN140413 fireball. The operation of these systems is explained in [1,2]. Some of these are configured as spectrographs by attaching holographic diffraction gratings (1000 lines/mm) to the objective lens [3]. To calculate the atmospheric trajectory, radiant, and orbit we have employed our AMALTHEA software, which follows the planes intersection method [4]. The spectrum was analyzed with our CHIMET application [5]. The parent meteoroid impacted the atmosphere with an initial velocity of 28.9 ± 0.3 km/s and the fireball began at a height of 104.4 ± 0.5 km. The event ended at 80.7 ± 0.5 km above the ground level, with the main flare taking place at 83 ± 0.5 km. The calculated radiant and orbital parameters confirm the sporadic nature of the bolide. The calibrated emission spectrum shows that the most important contributions correspond to the Na I-1 (588.9 nm) and Mg I-2 (517.2 nm) multiplets. In the ultraviolet, the contribution from the H and K lines from Ca was also identified. As usual in meteor spectra, most of the lines correspond to Fe I. The train spectrum was recorded during about 0.12 seconds. This provided the evolution with time of the intensity of the emission lines in this signal. The contributions from Mg I, Na I, Ca I, Fe I, Ca II, and O I were identified in the afterglow, with the Na I-1

  4. The Onset of Gamma-Ray Burst Afterglow

    NASA Astrophysics Data System (ADS)

    Kobayashi, Shiho; Zhang, Bing

    2007-02-01

    We discuss the reference time t0 of afterglow light curves in the context of the standard internal-external shock model. The decay index of early afterglow is very sensitive to the reference time one chooses. In order to understand the nature of early afterglow, it is essential to take a correct reference time. Our simple analytic model provides a framework for understanding special relativistic effects involved in early afterglow phase. We evaluate light curves of reverse shock emission as well as those of forward shock emission, based on full hydrodynamic calculations. We show that the reference time does not shift significantly even in the thick-shell case. For external shock emission components, measuring times from the beginning of the prompt emission is a good approximation and it does not cause an early steep decay. In the thin-shell case, the energy transfer time from fireball ejecta to ambient medium typically extends to thousands of seconds. This might be related to the shallow decay phases observed in early X-ray afterglow at least for some bursts.

  5. Gamma-Ray Bursts: Afterglow and Prompt Emission Models

    NASA Astrophysics Data System (ADS)

    Zhang, Bing

    2008-10-01

    Swift observations have revealed interesting but puzzling data that demand a rethink of the origins of gamma-ray bursts (GRBs) and their afterglows. The chromatic breaks in X-ray/optical afterglow lightcurves stimulated several innovative suggestions, most invoking a non-forward-shock origin of the X-ray afterglows. The status of both the observational facts and the theoretical models is critically reviewed. Besides the late ``internal'' emission from a long-live central engine, most observed X-ray afterglows likely still include the contribution of the traditional forward shock component. The physical nature (e.g. energy dissipation mechanism, emission site, and radiation mechanism) of the GRB prompt emission is currently not identified. The motivations and issues of three proposed prompt emission sites are reviewed. Several independent methods, invoking prompt gamma-ray, X-ray, optical and GeV emission information, respectively, have been applied to constrain the unknown emission site. Tentative evidence suggests a large prompt emission radius. Finally, the implications of the broad band high quality data of the ``naked eye'' GRB 080319B for our understanding of the afterglow and prompt emission mechanisms are discussed.

  6. GRB 030329: 3 years of radio afterglow monitoring.

    PubMed

    van der Horst, A J; Kamble, A; Wijers, R A M J; Resmi, L; Bhattacharya, D; Rol, E; Strom, R; Kouveliotou, C; Oosterloo, T; Ishwara-Chandra, C H

    2007-05-15

    Radio observations of gamma-ray burst (GRB) afterglows are essential for our understanding of the physics of relativistic blast waves, as they enable us to follow the evolution of GRB explosions much longer than the afterglows in any other wave band. We have performed a 3-year monitoring campaign of GRB 030329 with the Westerbork Synthesis Radio Telescopes and the Giant Metrewave Radio Telescope. Our observations, combined with observations at other wavelengths, have allowed us to determine the GRB blast wave physical parameters, such as the total burst energy and the ambient medium density, as well as to investigate the jet nature of the relativistic outflow. Further, by modelling the late-time radio light curve of GRB 030329, we predict that the Low-Frequency Array (30-240 MHz) will be able to observe afterglows of similar GRBs, and constrain the physics of the blast wave during its non-relativistic phase.

  7. X-ray flares in early GRB afterglows.

    PubMed

    Burrows, D N; Falcone, A; Chincarini, G; Morris, D; Romano, P; Hill, J E; Godet, O; Moretti, A; Krimm, H; Osborne, J P; Racusin, J; Mangano, V; Page, K; Perri, M; Stroh, M

    2007-05-15

    The Swift X-ray Telescope (XRT) has discovered that flares are quite common in early X-ray afterglows of gamma-ray bursts (GRBs), being observed in roughly 50% of afterglows with prompt follow-up observations. The flares range in fluence from a few per cent to approximately 100% of the fluence of the prompt emission (the GRB). Repetitive flares are seen, with more than four successive flares detected by the XRT in some afterglows. The rise and fall times of the flares are typically considerably smaller than the time since the burst. These characteristics suggest that the flares are related to the prompt emission mechanism, but at lower photon energies. We conclude that the most likely cause of these flares is late-time activity of the GRB central engine.

  8. The Supercritical Pile GRB Model: The Prompt to Afterglow Evolution

    NASA Technical Reports Server (NTRS)

    Kazanas, Demosthenes

    2008-01-01

    The 'Supercritical Pile' is a very economical gamma ray burst (GRB) model that provides for the efficient conversion of the energy stored in the protons of a Relativistic Blast Wave (RBW) into radiation and at the same time produces - in the prompt GRB phase, even in the absence of any particle acceleration - a spectral peak at an energy sim 1 MeV. We extend this model to include also the evolution of the RBW Lorentz factor Gamma and thus follow the spectral and temporal features of this model into the early GRB afterglow stage. One of the novel features of the present treatment is the inclusion of the feedback of the GRB produced radiation on the evolution of Gamma with radius. This feedback and the presence of kinematic and dynamic thresholds in the model can be the sources of rich time evolution which we have begun to explore. In particular, one can this way obtain afterglow light curves with steep decays followed by the more conventional flatter afterglow slopes, while at the same time preserving the desirable features of the model, i.e. the well defined relativistic electron source and radiative processes that produce the proper peak in the nu F spectra. Furthermore, the existence of a kinematic threshold in this model provides for a operational distinction of the prompt and afterglow GRB stages; in fact, the afterglow stage sets in when the RBW Lorentz factor cannot anymore fulfill the kinematic condition for pair formation in the photon - proton pair production reactions that constitute the fundamental process for the dissipation of the blast wave kinetic energy. We present the results of a specific set of parameters of this model with emphasis on the multiwavelength prompt emission and transition to the early afterglow.

  9. Circular polarization in the optical afterglow of GRB 121024A.

    PubMed

    Wiersema, K; Covino, S; Toma, K; van der Horst, A J; Varela, K; Min, M; Greiner, J; Starling, R L C; Tanvir, N R; Wijers, R A M J; Campana, S; Curran, P A; Fan, Y; Fynbo, J P U; Gorosabel, J; Gomboc, A; Götz, D; Hjorth, J; Jin, Z P; Kobayashi, S; Kouveliotou, C; Mundell, C; O'Brien, P T; Pian, E; Rowlinson, A; Russell, D M; Salvaterra, R; di Serego Alighieri, S; Tagliaferri, G; Vergani, S D; Elliott, J; Fariña, C; Hartoog, O E; Karjalainen, R; Klose, S; Knust, F; Levan, A J; Schady, P; Sudilovsky, V; Willingale, R

    2014-05-08

    Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow polarization directly probes the magnetic properties of the jet when measured minutes after the burst, and it probes the geometric properties of the jet and the ambient medium when measured hours to days after the burst. High values of optical polarization detected minutes after the burst of GRB 120308A indicate the presence of large-scale ordered magnetic fields originating from the central engine (the power source of the GRB). Theoretical models predict low degrees of linear polarization and no circular polarization at late times, when the energy in the original ejecta is quickly transferred to the ambient medium and propagates farther into the medium as a blast wave. Here we report the detection of circularly polarized light in the afterglow of GRB 121024A, measured 0.15 days after the burst. We show that the circular polarization is intrinsic to the afterglow and unlikely to be produced by dust scattering or plasma propagation effects. A possible explanation is to invoke anisotropic (rather than the commonly assumed isotropic) electron pitch-angle distributions, and we suggest that new models are required to produce the complex microphysics of realistic shocks in relativistic jets.

  10. Measurements of EEDF in recombination dominated afterglow plasma

    NASA Astrophysics Data System (ADS)

    Plasil, R.; Korolov, I.; Kotrik, T.; Varju, J.; Dohnal, P.; Donko, Z.; Bano, G.; Glosik, J.

    2009-11-01

    Electron energy distribution functions (EEDF) have been measured in decaying plasma in Flowing Afterglow Langmuir Probe (FALP) experiment. The measurements have been carried out in diffusion and recombination governed plasmas used for studies of recombination of KrD+ and H3+ ions.

  11. Atmospheric pressure helium afterglow discharge detector for gas chromatography

    DOEpatents

    Rice, Gary; D'Silva, Arthur P.; Fassel, Velmer A.

    1986-05-06

    An apparatus for providing a simple, low-frequency electrodeless discharge system for atmospheric pressure afterglow generation. A single quartz tube through which a gas mixture is passed is extended beyond a concentric electrode positioned thereabout. A grounding rod is placed directly above the tube outlet to permit optical viewing of the discharge between the electrodes.

  12. Atmospheric pressure helium afterglow discharge detector for gas chromatography

    DOEpatents

    Rice, G.; D'Silva, A.P.; Fassel, V.A.

    1985-04-05

    An apparatus for providing a simple, low-frequency, electrodeless discharge system for atmospheric pressure afterglow generation. A single quartz tube through which a gas mixture is passed is extended beyond a concentric electrode positioned thereabout. A grounding rod is placed directly above the tube outlet to permit optical viewing of the discharge between the electrodes.

  13. DISCOVERY OF RADIO AFTERGLOW FROM THE MOST DISTANT COSMIC EXPLOSION

    SciTech Connect

    Chandra, Poonam; Frail, Dale A.; Fox, Derek; Kulkarni, Shrinivas; Harrsion, Fiona; Kasliwal, Mansi; Berger, Edo; Cenko, S. Bradley; Bock, Douglas C.-J.

    2010-03-20

    We report on the discovery of radio afterglow emission from the gamma-ray burst GRB 090423, which exploded at a redshift of 8.3, making it the object with the highest known redshift in the universe. By combining our radio measurements with existing X-ray and infrared observations, we estimate the kinetic energy of the afterglow, the geometry of the outflow, and the density of the circumburst medium. Our best-fit model suggests a quasi-spherical, high-energy explosion in a low, constant-density medium. GRB 090423 had a similar energy release to the other well-studied high redshift GRB 050904 (z = 6.26), but their circumburst densities differ by 2 orders of magnitude. We compare the properties of GRB 090423 with a sample of gamma-ray bursts (GRBs) at moderate redshifts. We find that the high energy and afterglow properties of GRB 090423 are not sufficiently different from other GRBs to suggest a different kind of progenitor, such as a Population III (Pop III) star. However, we argue that it is not clear that the afterglow properties alone can provide convincing identification of Pop III progenitors. We suggest that the millimeter and centimeter radio detections of GRB 090423 at early times contained emission from the reverse shock. If true, this may have important implications for the detection of high-redshift GRBs by the next generation of radio facilities.

  14. Polarization Evolution of the Afterglow of GRB 030329

    NASA Technical Reports Server (NTRS)

    Greiner, Jochen; Klose, Sylvio; Reinsch, Klaus; Schmid, Hans Martin; Sari, Re'em; Hartmann, Dieter H.; Kouveliotou, Chryssa; Rau, Arne; Palazzi, Eliana; Straubmeier, Christian

    2003-01-01

    The association of a supernova with GRB 030329l strongly supports the collapsar model of gamma-ray bursts (GRBs), where a relativistic jet forms after the progenitor star collapses. Such jets cannot be spatially resolved because of their cosmological distances. Their existence is conjectured based on breaks in GRB afterglow light curves and the theoretical desire to reduce the GRB energy requirements. Temporal evolution of polarization may provide independent evidence for the jet structure of the relativistic outflow. Small-level polarization (approx. 1-3%) has been reported for a few bursts, but the temporal evolution of polarization properties could not be established. Here, we report polarimetric observations of the afterglow of GRB 030329 with high signal-to-noise and high sampling frequency. We establish the polarization light curve, detect sustained polarization at the percent level, and find significant variability. The data imply that the afterglow magnetic field has small coherence length and is mostly random, probably generated by turbulence, in contrast with the high polarization detected in the prompt gamma-rays from GRB 02120618. Our results suggest a different structure and origin of the magnetic field in the prompt vs. afterglow emission regions.

  15. The Supercritical Pile GRB Model: The Prompt to Afterglow Evolution

    NASA Technical Reports Server (NTRS)

    Mastichiadis, A.; Kazanas, D.

    2009-01-01

    The "Supercritical Pile" is a very economical GRB model that provides for the efficient conversion of the energy stored in the protons of a Relativistic Blast Wave (RBW) into radiation and at the same time produces - in the prompt GRB phase, even in the absence of any particle acceleration - a spectral peak at energy approx. 1 MeV. We extend this model to include the evolution of the RBW Lorentz factor Gamma and thus follow its spectral and temporal features into the early GRB afterglow stage. One of the novel features of the present treatment is the inclusion of the feedback of the GRB produced radiation on the evolution of Gamma with radius. This feedback and the presence of kinematic and dynamic thresholds in the model can be the sources of rich time evolution which we have began to explore. In particular. one can this may obtain afterglow light curves with steep decays followed by the more conventional flatter afterglow slopes, while at the same time preserving the desirable features of the model, i.e. the well defined relativistic electron source and radiative processes that produce the proper peak in the (nu)F(sub nu), spectra. In this note we present the results of a specific set of parameters of this model with emphasis on the multiwavelength prompt emission and transition to the early afterglow.

  16. The local dissociation phenomenon in a nitrogen afterglow

    NASA Astrophysics Data System (ADS)

    Levaton, J.; Amorim, J.; Ricard, A.

    2012-12-01

    We used the optical emission spectroscopy diagnostic to study the nitrogen afterglow of a pure N2 flowing dc discharge operating under particular experimental conditions to facilitate the simultaneous occurrence of the pink afterglow (PA) and the Lewis-Rayleigh afterglow. The PA is a special kind of nitrogen plasma occurring outside the direct influence of an external electric field. The phenomenon results from the flux of energy, introduced in the nitrogen molecules by the electrons in the discharge region, from the lower to the higher N_{2}(X\\,^1\\Sigma _g^+ ) vibrational levels due to vibrational-vibrational (V-V) and vibrational-translational (V-T) exchange reactions. We studied the following set of experimental conditions: discharge electric current (I = 15-50 mA), gas pressure (p = 200-1070 Pa) and gas flow rate (Q = 400-1000 sccm). The emissions of the first positive system of the nitrogen molecules were monitored from the end of the discharge down to the end of the post-discharge tube. A kinetic numerical model developed to investigate the nitrogen afterglow generated a calibrating factor for the 580.4 nm band in such a way that the relative density of the N(4S) atoms could be measured along the afterglow. The experimental results indicated that N(4S) atoms are created locally in the afterglow producing atomic density profiles that follow the behaviour of the other species studied experimentally in the PA, such as N_{2}(A\\,^3\\Sigma _u^+ ) , N2(B 3Πg), N2(C 3Πu), N_2^+ (X\\,^2\\Sigma _g^+ ) , N_2^+ (B\\,^2\\Sigma _u^+ ) , N+, N_3^+ , N_4^+ , N(2D) and N(2P). The numerical model was also used to fit the N2(B 3Πg), N_2^+ (B\\,^2\\Sigma _u^+ ) and the N(4S) experimental density profiles and to evaluate the participation of several kinetic pathways capable of producing local dissociation in the N2 afterglow. It was found that the dominant dissociation channel in the PA is the reaction N_2 (a'\\,^1\\Sigma _u^- )+N_2 (X\\,^1\\Sigma _g^+ ,v>4)\\to N(^4S)+N(^4

  17. The SEDs and Host Galaxies of the Dustiest GRB Afterglows

    NASA Technical Reports Server (NTRS)

    Kruhler, T.; Greiner, J.; Schady, P.; Savaglio, S.; Afonso, P. M. J.; Clemens, C.; Elliott, J.; Filgas, R.; Gruber, D.; Kann, D. A.; Klose, S.; Kupcu-Yoldas, A.; McBreen, S.; Olivares, E.; Pierini, D.; Rau, A.; Rossi, A.; Nardini, M.; Nicuesa Guelbenzu, A.; Sudilovsky, V.; Updike, A. C.

    2011-01-01

    The afterglows and host galaxies of long gamma-ray bursts (GRBs) offer unique opportunities to study star-forming galaxies in the high-z Universe, Until recently, however. the information inferred from GRB follow-up observations was mostly limited to optically bright afterglows. biasing all demographic studies against sight-lines that contain large amounts of dust. Aims. Here we present afterglow and host observations for a sample of bursts that are exemplary of previously missed ones because of high visual extinction (A(sub v) (Sup GRB) approx > 1 mag) along the sight-line. This facilitates an investigation of the properties, geometry and location of the absorbing dust of these poorly-explored host galaxies. and a comparison to hosts from optically-selected samples. Methods. This work is based on GROND optical/NIR and Swift/XRT X-ray observations of the afterglows, and multi-color imaging for eight GRB hosts. The afterglow and galaxy spectral energy distributions yield detailed insight into physical properties such as the dust and metal content along the GRB sight-line as well as galaxy-integrated characteristics like the host's stellar mass, luminosity. color-excess and star-formation rate. Results. For the eight afterglows considered in this study we report for the first time the redshift of GRBs 081109 (z = 0.97S7 +/- 0.0005). and the visual extinction towards GRBs 0801109 (A(sub v) (Sup GRB) = 3.4(sup +0.4) (sub -0.3) mag) and l00621A (A(sub v) (Sup GRB) = 3.8 +/- 0.2 mag), which are among the largest ever derived for GRB afterglows. Combined with non-extinguished GRBs. there is a strong anti-correlation between the afterglow's metals-to-dust ratio and visual extinction. The hosts of the dustiest afterglows are diverse in their properties, but on average redder(((R - K)(sub AB)) approximates 1.6 mag), more luminous ( approximates 0.9 L (sup *)) and massive ((log M(sup *) [M(solar]) approximates 9.8) than the hosts of optically-bright events. We hence probe

  18. The SEDs and host galaxies of the dustiest GRB afterglows

    NASA Astrophysics Data System (ADS)

    Krühler, T.; Greiner, J.; Schady, P.; Savaglio, S.; Afonso, P. M. J.; Clemens, C.; Elliott, J.; Filgas, R.; Gruber, D.; Kann, D. A.; Klose, S.; Küpcü-Yoldaş, A.; McBreen, S.; Olivares, F.; Pierini, D.; Rau, A.; Rossi, A.; Nardini, M.; Nicuesa Guelbenzu, A.; Sudilovsky, V.; Updike, A. C.

    2011-10-01

    Context. The afterglows and host galaxies of long gamma-ray bursts (GRBs) offer unique opportunities to study star-forming galaxies in the high-z Universe. Until recently, however, the information inferred from GRB follow-up observations was mostly limited to optically bright afterglows, biasing all demographic studies against sight-lines that contain large amounts of dust. Aims: Here we present afterglow and host observations for a sample of bursts that are exemplary of previously missed ones because of high visual extinction (AVGRB ≳ 1 mag) along the sight-line. This facilitates an investigation of the properties, geometry, and location of the absorbing dust of these poorly-explored host galaxies, and a comparison to hosts from optically-selected samples. Methods: This work is based on GROND optical/NIR and Swift/XRT X-ray observations of the afterglows, and multi-color imaging for eight GRB hosts. The afterglow and galaxy spectral energy distributions yield detailed insight into physical properties such as the dust and metal content along the GRB sight-line and galaxy-integrated characteristics such as the host's stellar mass, luminosity, color-excess, and star-formation rate. Results: For the eight afterglows considered in this study, we report for the first time the redshift of GRB 081109 (z = 0.9787 ± 0.0005), and the visual extinction towards GRBs 081109 (AVGRB = 3.4-0.3+0.4 mag) and 100621A (AVGRB = 3.8±0.2 mag), which are among the largest ever derived for GRB afterglows. Combined with non-extinguished GRBs, there is a strong anti-correlation between the afterglow's metal-to-dust ratio and visual extinction. The hosts of the dustiest afterglows are diverse in their properties, but on average redder (⟨ (R - K)AB ⟩ ~ 1.6 mag), more luminous (⟨ L ⟩ ~ 0.9 L∗), and massive (⟨ log M∗ [M⊙] ⟩ ~ 9.8) than the hosts of optically-bright events. Hence, we probe a different galaxy population, suggesting that previous host samples miss most of the

  19. Molecular chemiluminescence from Mercury halides excited in an atmospheric-pressure active-nitrogen afterglow

    SciTech Connect

    Rice, G.W.; D'Silva, A.P.; Fassel, V.A.

    1985-05-01

    It is demonstrated that an atmospheric-pressure, active-nitrogen (APAN) afterglow can be used as an excitation source for HgCl/sub 2/, HgBr/sub 2/, and HgI/sub 2/ introduced into the afterglow. The emission spectra obtained upon the introductiion of HgCl/sub 2/, HgBr/sub 2/, and HgI/sub 2/ vapors into the APAN afterglow are presented. (AIP)

  20. Simulation Study Of Early Afterglows Observed With Swift

    NASA Astrophysics Data System (ADS)

    Nishikawa, Ken-Ichi; Hededal, C.; Hardee, P.; Mizuno, Y.; Fishman, G. J.

    2006-09-01

    A 3-D relativistic particle-in-cell code has been used to simulate the dynamics of forward and reverse shocks with thin and thick shells within the parameter constraints provided by present Swift observations and the present models of GRB emission. Our 3-D RPIC simulations have provided the dynamics of collisionless shocks in electron-ion and electron-positron plasmas with and without initial ambient magnetic fields and revealed the importance of ``jitter radiation'' with prompt and afterglow spectra due to the inhomogeneous magnetic fields generated by the Weibel instability. It is different from synchrotron radiation, which is usually assumed to be the dominant radiation process. We have investigated gamma-ray burst emissions from prompt, early, and late afterglows considering microscopic processes. Based on our previous investigation of the Weibel instability for each stage of evolution of ejecta propagating in the ISM, we have incorporated the plasma conditions (relativistic jets) with the density and composition of the plasmas, the magnetic field strength ($\\sigma$-values (the ratio of the electromagnetic energy flux to the particle energy flux)) and its direction, and the Lorentz factor for the different stages in prompt and afterglows. Systematic simulation studies of the relativistic collisionless shocks, associated particle acceleration, magnetic field generation and self-consistent radiation provide insight into undetermined issues in prompt and afterglows observed by Swift. Self-consistently calculated lightcurves, spectra, spectral evolutions, and polarization as function of viewing angle will be done to light a shed on recent new observations by Swift, in particular, X-ray flares, early steep decay, and shallow decay.

  1. Detailed Study of the Variable Afterglow of GRB 060526

    SciTech Connect

    Johannesson, G.; Thoene, C. C.; Fynbo, J. P. U.; Kann, D. A.; Selj, J. H.; Jaunsen, A.; Hanlon, L.; French, J.

    2009-05-25

    Using one of the largest photometric datasets ever obtained for a GRB, we investigate the highly variable afterglow light curve of Gamma-Ray Burst 060526. The light curve shows clear deviations from a power-law behaviour which we attribute to energy injections. We fit the data to a numerical model including 6 energy injections which explains the full temporal behaviour of the light curve in many wavebands, ranging from NIR to X-rays.

  2. Continuous heatable Langmuir probe for flowing afterglow measurements

    NASA Astrophysics Data System (ADS)

    Laubé, Sylvain; Mostefaoui, Toufik; Rowe, Bertrand

    2000-02-01

    A heatable Langmuir probe consisting of a continuous dc-heating-current loop of tungsten wire is presented. This technique is efficient to keep the probe surface clean for flowing afterglow measurements. In our experimental conditions, the perturbations on the electron density determination can be considered as very small. The measurement of the well-known rate for the dissociative recombination of O2+ shows that the gas surrounding the probe is not heated for estimated probe temperature up to 700 K.

  3. Spectroscopic Observations of the Bright Afterglow of GRB021004

    NASA Astrophysics Data System (ADS)

    Harrison, Fiona

    2001-09-01

    One of the holy grails of gamma-ray burst research is to detect X-ray line signatures from an afterglow with high statistical significance. Of all possible observations, this perhaps offers the best chance of constraining the GRB mechanism and environment, and could provide the "smoking gun" signature connecting GRBs to massive stellar deaths. In order to accomplish this, we know long observations within one day of the event are necessary.

  4. TWO POPULATIONS OF GAMMA-RAY BURST RADIO AFTERGLOWS

    SciTech Connect

    Hancock, P. J.; Gaensler, B. M.; Murphy, T.

    2013-10-20

    The detection rate of gamma-ray burst (GRB) afterglows is ∼30% at radio wavelengths, much lower than in the X-ray (∼95%) or optical (∼70%) bands. The cause of this low radio detection rate has previously been attributed to limited observing sensitivity. We use visibility stacking to test this idea, and conclude that the low detection rate is instead due to two intrinsically different populations of GRBs: radio-bright and radio-faint. We calculate that no more than 70% of GRB afterglows are truly radio-bright, leaving a significant population of GRBs that lack a radio afterglow. These radio-bright GRBs have higher gamma-ray fluence, isotropic energies, X-ray fluxes, and optical fluxes than the radio-faint GRBs, thus confirming the existence of two physically distinct populations. We suggest that the gamma-ray efficiency of the prompt emission is responsible for the difference between the two populations. We also discuss the implications for future radio and optical surveys.

  5. Study of argon flowing afterglow with nitrogen injection

    SciTech Connect

    Mazánková, V.; Krčma, F.; Trunec, D.

    2013-10-28

    In this work, the reaction kinetics in argon flowing afterglow with nitrogen addition was studied by optical emission spectroscopy. The DC flowing post-discharge in pure argon was created in quartz tube at the total gas pressure of 1000 Pa and discharge power of 60 W. The nitrogen was added into the afterglow at the distance of 9 cm behind the active discharge. The optical emission spectra were measured along the flow tube. The argon spectral lines and after nitrogen addition also nitrogen second positive system (SPS) were identified in the spectra. The measurement of spatial dependence of SPS intensity showed a very slow decay of the intensity and the decay rate did not depend on the nitrogen concentration. In order to explain this behavior a kinetic model for reaction in afterglow was developed. This model showed that C {sup 3}Π{sub u} state of molecular nitrogen, which is the upper state of SPS emission, is produced by excitation transfer from argon metastables to nitrogen molecules. However, the argon metastables are also produced at Ar{sub 2}{sup +} ion recombination with electrons and this limits the decay of argon metastable concentration and it results in very slow decay of SPS intensity.

  6. Rates, flux densities, and spectral indices of meteor radio afterglows

    NASA Astrophysics Data System (ADS)

    Obenberger, K. S.; Dowell, J. D.; Hancock, P. J.; Holmes, J. M.; Pedersen, T. R.; Schinzel, F. K.; Taylor, G. B.

    2016-07-01

    Using the narrowband all-sky imager mode of the Long Wavelength Array (LWA1), we have now detected 30 transients at 25.6 MHz, 1 at 34 MHz, and 93 at 38.0 MHz. While we have only optically confirmed that 37 of these events are radio afterglows from meteors, evidence suggests that most, if not all, are. Using the beam-forming mode of the LWA1, we have also captured the broadband spectra between 22.0 and 55.0 MHz of four events. We compare the smooth, spectral components of these four events and fit the frequency-dependent flux density to a power law, and find that the spectral index is time variable, with the spectrum steepening over time for each meteor afterglow. Using these spectral indices along with the narrowband flux density measurements of the 123 events at 25.6 and 38 MHz, we predict the expected flux densities and rates for meteor afterglows potentially observable by other low-frequency radio telescopes.

  7. Numerical Simulation of Flares in GRB Afterglow Phase

    NASA Astrophysics Data System (ADS)

    Meliani, Z.; Vlasis, A.; Keppens, R.

    2012-07-01

    We investigate numerically the various evolutionary phases in the interaction of relativistic shells with its surrounding cold interstellar medium (ISM) and shell-shell interaction. We do this for 1D. This is relevant for gamma-ray bursts (GRBs) and the observed flares, and we demonstrate that, thanks to the AMR strategy, we resolve the internal structure of the shocked shell and ISM matter and shell-shell matter, which will leave its imprint on the GRB afterglow. Also, we perform high resolution numerical simulations of late collisions between two ultra-relativistic shells in order to explore the flares in the afterglow phase of GRB. We examine the case where a cold uniform shell collides with a self-similar Blandford and McKee shell in a constant density environment and consider cases with different Lorentz factor and energy for the uniform shell. We produce the corresponding on-axis light curves and emission images for the afterglow phase and examine the occurrence of optical and radio flares assuming a spherical explosion and a hard-edged jet scenario. For our simulations we use the Adaptive Mesh Refinement version of the Versatile Advection Code (AMRVAC) coupled to a linear radiative transfer code to calculate synchrotron emission. We find steeply rising flare like behavior for small jet opening angles and more gradual rebrightenings for large opening angles. Synchrotron self-absorption is found to strongly influence the onset and shape of the radio flare.

  8. Effect of secondary emission on the argon plasma afterglow with large dust density

    SciTech Connect

    Denysenko, I. B.; Azarenkov, N. A.; Burmaka, G. P.; Stefanović, I.

    2015-02-15

    A zero-dimensional, space-averaged model for argon plasma afterglow with large dust density is developed. In the model, three groups of electrons in the plasma afterglow are assumed: (i) thermal electrons with Maxwellian distribution, (ii) energetic electrons generated by metastable-metastable collisions (metastable pooling), and (iii) secondary electrons generated at collisions of ions with the electrodes, which have sufficiently large negative voltages in the afterglow. The model calculates the time-dependencies for electron densities in plasma afterglow based on experimental decay times for metastable density and electrode bias. The effect of secondary emission on electron density in the afterglow is estimated by varying secondary emission yields. It is found that this effect is less important than metastable pooling. The case of dust-free plasma afterglow is considered also, and it is found that in the afterglow the effect of secondary emission may be more important than metastable pooling. The secondary emission may increase thermal electron density n{sub e} in dust-free and dusty plasma afterglows on a few ten percentages. The calculated time dependencies for n{sub e} in dust-free and dusty plasma afterglows describe well the experimental results.

  9. 'Self-absorbed' GeV light curves of gamma-ray burst afterglows

    SciTech Connect

    Panaitescu, A.; Vestrand, W. T.; Woźniak, P.

    2014-06-10

    We investigate the effect that the absorption of high-energy (above 100 MeV) photons produced in gamma-ray burst afterglow shocks has on the light curves and spectra of Fermi Large Area Telescope (LAT) afterglows. Afterglows produced by the interaction of a relativistic outflow with a wind-like medium peak when the blast wave deceleration sets in, and the afterglow spectrum could be hardening before that peak, as the optical thickness to pair formation is decreasing. In contrast, in afterglows produced in the interaction with a homogeneous medium, the optical thickness to pair formation should increase and yield a light curve peak when it reaches unity, followed by a fast light curve decay, accompanied by spectral softening. If energy is injected in the blast wave, then the accelerated increase of the optical thickness yields a convex afterglow light curve. Other features, such as a double-peak light curve or a broad hump, can arise from the evolution of the optical thickness to photon-photon absorption. Fast decays and convex light curves are seen in a few LAT afterglows, but the expected spectral softening is rarely seen in (and difficult to measure with) LAT observations. Furthermore, for the effects of photon-photon attenuation to shape the high-energy afterglow light curve without attenuating it too much, the ejecta initial Lorentz factor must be in a relatively narrow range (50-200), which reduces the chance of observing those effects.

  10. GRB off-axis afterglows and the emission from the accompanying supernovae

    NASA Astrophysics Data System (ADS)

    Kathirgamaraju, Adithan; Barniol Duran, Rodolfo; Giannios, Dimitrios

    2016-09-01

    Gamma-ray burst (GRB) afterglows are likely produced in the shock that is driven as the GRB jet interacts with the external medium. Long-duration GRBs are also associated with powerful supernovae (SNe). We consider the optical and radio afterglows of long GRBs for both blasts viewed along the jet axis (`on-axis' afterglows) and misaligned observes (`off-axis' afterglows). Comparing the optical emission from the afterglow with that of the accompanying SN, using SN 1998bw as an archetype, we find that only a few per cent of afterglows viewed off-axis are brighter than the SN. For observable optical off-axis afterglows, the viewing angle is at most twice the half-opening angle of the GRB jet. Radio off-axis afterglows should be detected with upcoming radio surveys within a few hundred Mpc. We propose that these surveys will act as `radio triggers', and that dedicated radio facilities should follow-up these sources. Follow-ups can unveil the presence of the radio SN remnant, if present. In addition, they can probe the presence of a mildly relativistic component, either associated with the GRB jet or the SN ejecta, expected in these sources.

  11. Gamma-ray Bursts: Radio Afterglow and Host Galaxy Study with The FAST Telescope

    NASA Astrophysics Data System (ADS)

    Li, L. B.; Huang, Y. F.; Kong, S. W.; Zhang, Z. B.; Li, D.; Luo, J. J.

    2016-02-01

    For four types of GRBs, namely high-luminosity, low-luminosity, standard and failed GRBs, we calculated their radio afterglow light curves. Meanwhile, considering contributions from host galaxies in radio bands, we statistically investigated the effect of hosts on radio afterglows. It is found that a tight anti-correlation exists between the ratio of radio flux (RRF) of host galaxy to the total radio afterglow peak flux and the observed frequency. Using this method, the host flux densities of those bursts without host measurements can be estimated at low or medium frequencies. We predicted that almost all types of radio afterglows, except that of low-luminosity GRBs, can be observed by FAST up to z = 15 or even more. FAST is expected to significantly expand the samples of GRB radio afterglows and host galaxies.

  12. The Interpretation of the Multi-wavelength Afterglow Emission of Short GRB 140903A

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Jin, Zhi-Ping; Wang, Yuan-Zhu; Wei, Da-Ming

    2017-01-01

    GRB 140903A, a short duration γ-ray burst (SGRB) detected by Swift, is characterized by its long-lasting radio emission among SGRBs. In addition to the ∼ {10}6 s radio afterglow emission, the afterglow of GRB 140903A displays a plateau from 103 s to 7× {10}3 {{s}} in the X-rays. In this work, we attribute the X-ray plateau to the energy injection into the decelerating blast wave and then model the later radio/optical/X-ray afterglow emission within the standard fireball afterglow model. The afterglow emission has been well reproduced with reasonable physical parameters, including a jet half-opening angle of ∼0.05.

  13. Spectral Energy Distributions and Light Curves of GRB 990123 and its Afterglow

    NASA Technical Reports Server (NTRS)

    Galama, T. J.; Briggs, M. S.; Wijers, R. A. M. J.; Vreeswijk, P. M.; Rol, E.; Band, D.; VanParadijs, J.; Kouveliotou, C.; Preece, R. D.; Bremer, M.

    1999-01-01

    Investigations of the 'fireball' model currently believed to explain the prompt gamma-ray and afterglow emissions of gamma-ray bursts. On January 23 a gamma-ray burst (GRB) occurred for which for the first time prompt optical emission was detected. We here report the results of gamma-ray, optical/infrared, sub-mm, mm and radio observations of this burst and its afterglow, which indicate that the prompt and afterglow emissions from GRB 990123 are associated with three distinct regions in the fireball. The afterglow synchrotron spectrum one day after the burst has a much lower peak frequency than those of previous bursts; this explains the short-lived nature of the radio emission, which is not expected to reappear. We suggest that such differences reflect variations in the magnetic-field strengths in the afterglow emitting regions.

  14. Afterglow Study of ZnS:Cu,Co Water-soluble Nanoparticles and Potential Applications

    NASA Astrophysics Data System (ADS)

    Ma, Lun; Chen, Wei

    2011-03-01

    ZnS:Cu,Co water-soluble afterglow particles with average size of 4 nm have been prepared by using simple wet chemistry method. The X-ray diffraction pattern of the nanoparticles shows a cubic zinc blende structure as the synthesis temperature is low comparing with solid state reactions. The nanoparticles have two photoluminescence emission peaks. The blue emission is from sulfur defects (vacancies), while the green emission is from Cu 2+ luminescent center which also contributes to the particle's afterglow. The presence of co-dopant Co 2+ is critical to perform the afterglow of these nanoparticles. The afterglow intensity and decay vary on different Cu 2+ and Co 2+ doping levels. Further conjugation of ZnS:Cu,Co nanoparticles and photosensitizers presents a new method for deep cancer treatment in photodynamic therapy. The successful afterglow observation from water-soluble nanoparticles may find many new applications in biological imaging, detection and treatment.

  15. Study of nitrogen flowing afterglow with mercury vapor injection

    SciTech Connect

    Mazánková, V. Krčma, F.; Trunec, D.

    2014-10-21

    The reaction kinetics in nitrogen flowing afterglow with mercury vapor addition was studied by optical emission spectroscopy. The DC flowing post-discharge in pure nitrogen was created in a quartz tube at the total gas pressure of 1000 Pa and discharge power of 130 W. The mercury vapors were added into the afterglow at the distance of 30 cm behind the active discharge. The optical emission spectra were measured along the flow tube. Three nitrogen spectral systems – the first positive, the second positive, and the first negative, and after the mercury vapor addition also the mercury resonance line at 254 nm in the spectrum of the second order were identified. The measurement of the spatial dependence of mercury line intensity showed very slow decay of its intensity and the decay rate did not depend on the mercury concentration. In order to explain this behavior, a kinetic model for the reaction in afterglow was developed. This model showed that the state Hg(6 {sup 3}P{sub 1}), which is the upper state of mercury UV resonance line at 254 nm, is produced by the excitation transfer from nitrogen N{sub 2}(A{sup 3}Σ{sup +}{sub u}) metastables to mercury atoms. However, the N{sub 2}(A{sup 3}Σ{sup +}{sub u}) metastables are also produced by the reactions following the N atom recombination, and this limits the decay of N{sub 2}(A{sup 3}Σ{sup +}{sub u}) metastable concentration and results in very slow decay of mercury resonance line intensity. It was found that N atoms are the most important particles in this late nitrogen afterglow, their volume recombination starts a chain of reactions which produce excited states of molecular nitrogen. In order to explain the decrease of N atom concentration, it was also necessary to include the surface recombination of N atoms to the model. The surface recombination was considered as a first order reaction and wall recombination probability γ = (1.35 ± 0.04) × 10{sup −6} was determined from the experimental data. Also

  16. Fermi and Swift Gamma-Ray Burst Afterglow Population Studies

    NASA Technical Reports Server (NTRS)

    Racusin, J. L.; Oates, S. R.; Schady, P.; Burrows, D. N.; de Pasquale, M.; Donato, D.; Gehrels, N.; Koch, S.; McEnery, J.; Piran, T.; Roming, P.; Sakamoto, T.; Swenson, C.; Virgili, F.; Wanderman, D.; Zhang, B.

    2011-01-01

    The new and extreme population of GRBs detected by Fermi-LAT shows several new features in high energy gamma-rays that are providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last 6 years, it has been Swift that has provided the robust data set of UV/optical and X-ray afterglow observations that opened many windows into components of GRB emission structure. The relationship between the LAT GRBs and the well studied, fainter, less energetic GRBs detected by Swift-BAT is only beginning to be explored by multiwavelength studies. We explore the large sample of GRBs detected by BAT only, BAT and Fermi-GBM, and GBM and LAT, focusing on these samples separately in order to search for statistically significant differences between the populations, using only those GRBs with measured redshifts in order to physically characterize these objects. We disentangle which differences are instrumental selection effects versus intrinsic properties, in order to better understand the nature of the special characteristics of the LAT bursts.

  17. Fermi and Swift Gamma-Ray Burst Afterglow Population Studies

    NASA Technical Reports Server (NTRS)

    Racusin, Judith L.; Oates, S. R.; Schady, P.; Burrows, D. N.; dePasquale, M.; Donato, D.; Gehrels, N.; Koch, S.; McEnery, J.; Piran, T.; Roming, P.; Sakamoto, T.; Swenson, C.; Troja, E.; Vasileiou, V.; Virgili, F.; Wanderman, D.; Zhang, B.

    2011-01-01

    The new and extreme population of GRBs detected by Fermi -LAT shows several new features in high energy gamma-rays that are providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last 6 years, it has been Swift that has provided the robust dataset of UV/optical and X-ray afterglow observations that opened many windows into components of GRB emission structure. The relationship between the LAT detected GRBs and the well studied, fainter, less energetic GRBs detected by Swift -BAT is only beginning to be explored by multi-wavelength studies. We explore the large sample of GRBs detected by BAT only, BAT and Fermi -GBM, and GBM and LAT, focusing on these samples separately in order to search for statistically significant differences between the populations, using only those GRBs with measured redshifts in order to physically characterize these objects. We disentangle which differences are instrumental selection effects versus intrinsic properties, in order to better understand the nature of the special characteristics of the LAT bursts.

  18. Fermi and Swift Gamma-Ray Burst Afterglow Population Studies

    NASA Technical Reports Server (NTRS)

    Racusin, Judith I.

    2011-01-01

    The new and extreme population of GRBs detected by Fermi-LAT shows several new features in high energy gamma-rays that are providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last 6 years, it has been Swift that has provided the robust data set of UV/optical and X-ray afterglow observations that opened many windows into components of GRB emission structure. The relationship between the LAT GRBs and the well studied, fainter, less energetic GRBs detected by Swift-BAT is only beginning to be explored by multi-wavelength studies. We explore the large sample of GRBs detected by BAT only, BAT and Fermi-GBM, and GBM and LAT, focusing on these samples separately in order to search for statistically significant differences between the populations, using only those GRBs with measured redshifts in order to physically characterize these objects. We disentangle which differences are instrumental selection effects versus intrinsic properties, in order to better understand the nature of the special characteristics of the LAT bursts.

  19. Delayed energy injection model for gamma-ray burst afterglows

    SciTech Connect

    Geng, J. J.; Huang, Y. F.; Yu, Y. B.; Wu, X. F. E-mail: xfwu@pmo.ac.cn

    2013-12-10

    The shallow decay phase and flares in the afterglows of gamma-ray bursts (GRBs) are widely believed to be associated with the later activation of the central engine. Some models of energy injection involve a continuous energy flow since the GRB trigger time, such as the magnetic dipole radiation from a magnetar. However, in the scenario involving a black hole accretion system, the energy flow from the fall-back accretion may be delayed for a fall-back time ∼t {sub fb}. Thus, we propose a delayed energy injection model. The delayed energy would cause a notable rise to the Lorentz factor of the external shock, which will 'generate' a bump in the multiple band afterglows. If the delayed time is very short, our model degenerates to the previous models. Our model can explain the significant re-brightening in the optical and infrared light curves of GRB 081029 and GRB 100621A. A considerable fall-back mass is needed to provide the later energy; this indicates that GRBs accompanied with fall-back material may be associated with a low energy supernova so that the fraction of the envelope can survive during eruption. The fall-back time can give meaningful information on the properties of GRB progenitor stars.

  20. Testing a new view of gamma-ray burst afterglows

    NASA Astrophysics Data System (ADS)

    Nardini, M.; Ghisellini, G.; Ghirlanda, G.; Celotti, A.

    2010-04-01

    The optical and X-ray light curves of long gamma-ray bursts (GRBs) often show a complex evolution and in most cases do not track each other. This behaviour cannot be easily explained by the simplest standard afterglow models. A possible interpretation is to consider the observed optical and X-ray light curves as the sum of two separate components. This scenario requires the presence of a spectral break between these bands. One of the aims of this work is to test whether such a break is present within the observed Swift X-Ray Telescope energy range. We analyse the X-ray afterglow spectra of a sample of 33 long GRBs with known redshift, good optical photometry and published estimate of the host galaxy dust absorption AhostV. We find that indeed in seven bright events a broken power law provides a fit to the data that is better than a single power-law model. For eight events, instead, the X-ray spectrum is better fitted by a single power law. We discuss the role of these breaks in connection to the relation between the host hydrogen column density NhostH and AhostV and check the consistency of the X-ray spectral breaks with the optical bands photometry. We analyse the optical to X-ray spectral energy distributions at different times and find again consistency with two components interpretation.

  1. Testing an unifying view of Gamma Ray Burst afterglows

    NASA Astrophysics Data System (ADS)

    Nardini, M.; Ghisellini, G.; Ghirlanda, G.; Celotti, A.

    2011-04-01

    Four years after the launch the Swift satellite the nature of the Gamma Ray Bursts (GRBs) broadband afterglow behaviour is still an open issue. The standard external shock fireball model cannot easily explain the combined temporal and spectral properties of optical to X-ray afterglows. We analysed the rest frame de-absorbed and K-corrected optical and X-ray light curves of a sample of 33 GRBs with known redshift and optical extinction at the host frame. We modelled their broadband behaviour as the sum of the standard forward shock emission due to the interaction of a fireball with the circum-burst medium and an additional component. This description provides a good agreement with the observed light curves despite their complexity and diversity and can also account for the lack of achromatic late times jet breaks and the presence of chromatic breaks in several GRBs lightcurves. In order to test the predictions of such modelling we analysed the X-ray time resolved spectra searching for possible spectral breaks within the observed XRT energy band, finding seven GRBs showing such a break. The optical to X-ray SED evolution of these GRBs are consistent with what expected by our interpretation.

  2. Time Resolved Spectroscopy of a Leonid Fireball Afterglow

    NASA Astrophysics Data System (ADS)

    Borovička, Jiří.; Jenniskens, Peter

    Two video spectra of a meteoric afterglow were obtained for the first time during the 1999 Leonid aircraft campaign. The train was produced by a -13 magnitude Leonid fireball at a relatively low height between 91-75 km. The meteor spectrum has a strong hydrogen emission, proportional to 10-20 II atoms per one Fe atom The train spectrum consisted of a red continuum, yellow continuum, and about 50 atomic lines between 3700-9000 Å. The yellow continuum, possibly due to NO_2, was also detected in the persistent train. The red continuum is interpreted as a thermal radiation of dust from meteoric debris at about 1400 K. Evidence for secondary ablation is found in the afterglow. The atomic lines decayed within seconds of the meteor. The lines of Fe I, Mg I, Na I, Ca I, Ca II, Cr I, Mn I, K I, and possibly Al I were present in the glow together with the 5577 Å forbidden O I line. The gas temperature in the train was close to 5000 K at the beginning and decayed to 1200 K within two seconds. However, thermal equilibrium was not satisfied for all populated levels.

  3. Late activity in GRB afterglows. A multidimensional approach.

    NASA Astrophysics Data System (ADS)

    Vlasis, A.; Meliani, Z.; Keppens, R.

    A late activity of the central engine of Gamma-Ray Bursts (GRBs) followed by energy injection in the external shock has been proposed in order to explain the strong variability which is often observed in multiwavelength observations in the afterglow. We perform high resolution 1D and 2D numerical simulations of late collisions between two ultra-relativistic shells in order to explore these events. We examine the case where a cold uniform shell collides with a self-similar Blandford and McKee shell in a constant density environment and for the 1D case we produce the corresponding on-axis light curves for the afterglow phase investigating the occurrence of optical and radio flares assuming a spherical explosion and a jet scenario with different opening angles. For our simulations we use the Adaptive Mesh Refinement version of the Versatile Advection Code (MPI-AMRVAC) coupled to a linear radiative transfer code to calculate synchrotron emission. We find steeply rising flare like behavior for small jet opening angles and more gradual rebrightenings for large opening angles. Synchrotron self-absorption is found to strongly influence the onset and shape of the radio flare. Preliminary results of the dynamics from the 2D simulation are also presented in this paper.

  4. Afterglows of Mildly Relativistic Supernovae: Baryon Loaded Blastwaves

    NASA Astrophysics Data System (ADS)

    Chakraborti, Sayan; Ray, Alak

    2011-08-01

    Relativistic supernovae have been discovered until recently only through their association with long duration Gamma Ray Bursts (GRB). As the ejecta mass is negligible in comparison to the swept up mass, the blastwaves of such explosions are well described by the Blandford-McKee (in the ultra relativistic regime) and Sedov-Taylor (in the non-relativistic regime) solutions during their afterglows. However, the recent discovery of the relativistic supernova SN 2009bb, without a detected GRB, has indicated the possibility of highly baryon loaded mildly relativistic outflows which remains in nearly free expansion phase during the radio afterglow. In this work, we consider the dynamics and emission from a massive, relativistic shell, launched by a Central Engine Driven EXplosion (CEDEX), decelerating adiabatically due to its collision with the pre-explosion circumstellar wind profile of the progenitor. We show that this model explains the observed radio evolution of the prototypical SN 2009bb and demonstrate that SN 2009bb had a highly baryon loaded, mildly relativistic outflow.

  5. ZnS:Cu,Co water-soluble afterglow nanoparticles: synthesis, luminescence and potential applications.

    PubMed

    Ma, Lun; Chen, Wei

    2010-09-24

    Cu(2+) and Co(2+) co-doped zinc sulfide water-soluble nanoparticles (ZnS:Cu,Co) were prepared and their afterglow luminescence was observed and reported for the first time. The nanoparticles have a cubic zinc blende structure with average sizes of about 4 nm as determined by high-resolution transmission electron microscopy (HRTEM) and x-ray diffraction (XRD). In the photoluminescence, two emission peaks are observed at 470 and 510 nm. However, in the afterglow, only one peak is observed at around 525 nm. The blue emission at 470 nm is from surface states and the green emission at 525 nm is from Cu(2+). This means that Cu(2+) is responsible for the afterglow from the nanoparticles, while the co-doping of Co(2+) is critical for the afterglow because no afterglow could be seen without co-doping with Co(2+). The successful observation of the afterglow from water-soluble nanoparticles may open up new applications of afterglow phosphors in biological imaging, detection and treatment.

  6. ZnS:Cu,Co water-soluble afterglow nanoparticles: synthesis, luminescence and potential applications

    NASA Astrophysics Data System (ADS)

    Ma, Lun; Chen, Wei

    2010-09-01

    Cu2 + and Co2 + co-doped zinc sulfide water-soluble nanoparticles (ZnS:Cu,Co) were prepared and their afterglow luminescence was observed and reported for the first time. The nanoparticles have a cubic zinc blende structure with average sizes of about 4 nm as determined by high-resolution transmission electron microscopy (HRTEM) and x-ray diffraction (XRD). In the photoluminescence, two emission peaks are observed at 470 and 510 nm. However, in the afterglow, only one peak is observed at around 525 nm. The blue emission at 470 nm is from surface states and the green emission at 525 nm is from Cu2 + . This means that Cu2 + is responsible for the afterglow from the nanoparticles, while the co-doping of Co2 + is critical for the afterglow because no afterglow could be seen without co-doping with Co2 + . The successful observation of the afterglow from water-soluble nanoparticles may open up new applications of afterglow phosphors in biological imaging, detection and treatment.

  7. GRB 990712: First Detection of Polarization Variability in a Gamma-ray Burst Afterglow

    NASA Technical Reports Server (NTRS)

    Rol, E.; Wijers, R. A. M. J.; Vreeswijk, P. M.; Galama, T. J.; vanParadijs, J.; Kouveliotou, C.; Pian, E.; Palazzi, E.; Frontera, F.

    2000-01-01

    We report the detection of significant polarization in the afterglow of GRB 990712 on three instances 0.44-1.45 days after the gamma-ray burst. This polarization is intrinsic to the afterglow. The degree of polarization is not constant, and smallest at the second measurement. The polarization angle does not vary significantly during these observations. We find that none of the existing models predict such polarization variations constant polarization angle, and discuss ways in which these models might be modified to accommodate the observed behavior of this afterglow.

  8. The Swift Discovery of X-ray Afterglows Accompanying Short Bursts from SGR 1900+14

    NASA Technical Reports Server (NTRS)

    Nakagawa, Y. E.; Sakamoto, T.; Sato, G.; Gehrels, N.; Hurley, K.; Palmer, D. M.

    2008-01-01

    The discovery of X-ray afterglows accompanying two short bursts from SGR1900+14 is presented. The afterglow luminosities at the end of each observation are lower by 30-50% than their initial luminosities, and decay with power law indices p approx. 0.2-0.4. Their initial bolometric luminosities are L approx. 10(exp 34)- 10(exp 35) erg/s. We discuss analogies and differences between the X-ray afterglows of SGR short bursts and short gamma-ray bursts.

  9. Metastable atomic species in the N2 flowing afterglow

    NASA Astrophysics Data System (ADS)

    Levaton, J.; Amorim, J.

    2012-03-01

    We have studied by optical emission spectroscopy the post-discharge of a pure N2 DC flowing discharge in such experimental conditions that the pink afterglow and the Lewis-Rayleigh afterglow occur. The emission profiles originated from the NB3Πg, NC3Πu and N2+B2Σu+ states and the NB3Πg,6≤v≤12 and NC3Πu,0≤v≤4 vibrational distributions were obtained in the post-discharge region. With basis on the works of Bockel et al. [S. Bockel, A.M. Diamy, A. Ricard, Surf. Coat. Tech. 74 (1995) 474] and Amorim and Kiohara [J. Amorim, V. Kiohara, Chem. Phys. Lett. 385 (2004) 268], we have obtained the experimental N(4S) and N(2D) relative densities along the post-discharge. A numerical model, previously developed to describe the neutral atomic, molecular and ionic species in the afterglow, was improved to include the kinetics of N(2D) and N(2P) states. Several kinetic mechanisms leading to the production of N(2D) in the post-discharge have been studied in order to explain the experimental data. We have determined that the dominant one is the reaction NX1Σg+,v>8+N(4S)→NX1Σg++N(2D) with an estimated rate constant of 7 × 10-14 cm3 s-1. Also, the fit of the numerical density profiles of NC3Πu and N2+B2Σu+ to the experimental ones has provided the rate constant for reaction NA3Σu++NX1∑g+,v>18→NC3Πu+NX1Σg+. Its estimated value is 4 × 10-13 cm3 s-1. Finally, with the new kinetic scheme, we have found that the ionization in the post-discharge region has important contribution of N(2D) and N(2P) species.

  10. Pink splash of active nitrogen in the discharge afterglow

    SciTech Connect

    Akishev, Yu. S.; Grushin, M. E.; Karal'nik, V. B.; Petryakov, A. V.; Trushkin, N. I.

    2007-09-15

    Results are presented from experimental studies of the glow dynamics of active nitrogen in the stage of its excitation by a current pulse and during the discharge afterglow. The mechanism is proposed for the generation of a light splash in a highly activated nitrogen after the end of its pulsed excitation. The key role in the generation of this splash is played by the D-V processes, by which the dissociation energy is transferred to the vibrational degrees of freedom in the course of recombination of nitrogen atoms, and the V-E processes, by which the vibrational energy of highly excited molecules N{sub 2}(X, v {>=} 25-27) is transferred to the emitting electronic states N{sub 2}(B, v) after the V-V delay. Results of simulations based on the mechanism proposed are also presented.

  11. Langmuir-probe measurements in flowing-afterglow plasmas

    SciTech Connect

    Johnsen, R.; Shun'ko, E.V.; Gougousi, T. ); Golde, M.F. )

    1994-11-01

    The validity of the orbital-motion theory for cylindrical Langmuir probes immersed in flowing-afterglow plasmas is investigated experimentally. It is found that the probe currents scale linearly with probe area only for electron-collecting but not for ion-collecting probes. In general, no agreement is found between the ion and electron densities derived from the probe currents. Measurements in recombining plasmas support the conclusion that only the [ital electron] densities derived from probe measurements can be trusted to be of acceptable accuracy. This paper also includes a brief derivation of the orbital-motion theory, a discussion of perturbations of the plasma by the probe current, and the interpretation of plasma velocities obtained from probe measurements.

  12. Langmuir-Probe Measurements in Flowing-Afterglow Plasmas

    NASA Technical Reports Server (NTRS)

    Johnsen, R.; Shunko, E. V.; Gougousi, T.; Golde, M. F.

    1994-01-01

    The validity of the orbital-motion theory for cylindrical Langmuir probes immersed in flowing- afterglow plasmas is investigated experimentally. It is found that the probe currents scale linearly with probe area only for electron-collecting but not for ion-collecting probes. In general, no agreement is found between the ion and electron densities derived from the probe currents. Measurements in recombining plasmas support the conclusion that only the electron densities derived from probe measurements can be trusted to be of acceptable accuracy. This paper also includes a brief derivation of the orbital-motion theory, a discussion of perturbations of the plasma by the probe current, and the interpretation of plasma velocities obtained from probe measurements.

  13. Langmuir-probe measurements in flowing-afterglow plasmas

    NASA Astrophysics Data System (ADS)

    Johnsen, R.; Shun'ko, E. V.; Gougousi, T.; Golde, M. F.

    1994-11-01

    The validity of the orbital-motion theory for cylindrical Langmuir probes immersed in flowing-afterglow plasmas is investigated experimentally. It is found that the probe currents scale linearly with probe area only for electron-collecting but not for ion-collecting probes. In general, no agreement is found between the ion and electron densities derived from the probe currents. Measurements in recombining plasmas support the conclusion that only the electron densities derived from probe measurements can be trusted to be of acceptable accuracy. This paper also includes a brief derivation of the orbital-motion theory, a discussion of perturbations of the plasma by the probe current, and the interpretation of plasma velocities obtained from probe measurements.

  14. Bright afterglow illuminator made of phosphorescent material and fluorescent fibers.

    PubMed

    Saito, M; Yamamoto, K

    2000-08-20

    Phosphorescent oxides and fluorescent dyes were used together to create a fiber-type illuminator that glows in the dark without the need for electric power. Dye-doped polymer fibers, which were bundled at one end, were linearly arrayed in a polysiloxane resin that contained phosphorescent oxide particles. The phosphorescent resin continued to glow for a long time even after the excitation light was removed. Organic dyes in a polymer fiber were excited by the phosphorescence and emitted fluorescence toward the fiber end. Fluorescence from a number of dyes was combined in the long fiber, and, consequently a bright light beam emerged from the fiber end. Useful performance, i.e., high power density, narrow beam divergence, and long afterglow, is demonstrated by the prototype fiber illuminator.

  15. Rapid Identification of GRB Afterglows with Swift/UVOT

    NASA Technical Reports Server (NTRS)

    Marshall, F. E.

    2006-01-01

    As part of the automated response to a new gamma-ray burst (GRB), the Ultraviolet and Optical Telescope (UVOT) instrument on Swift starts a 200-second exposure with the V filter within approximately 100 seconds of the BAT burst trigger. The instrument searches for sources in a 8' x 8' region, and sends the list of sources and a 160" x 160" sub-image centered on the burst position to the ground via Tracking and Data Relay Satellite System (TDRSS). These raw products and additional products calculated on the ground are then distributed through the GCN within a few minutes of the trigger. We describe the sensitivity of these data for detecting afterglows, summarize current results, and outline plans for rapidly distributing future detections.

  16. Gamma-ray burst afterglows from transrelativistic blast wave simulations

    NASA Astrophysics Data System (ADS)

    van Eerten, H. J.; Leventis, K.; Meliani, Z.; Wijers, R. A. M. J.; Keppens, R.

    2010-03-01

    We present a study of the intermediate regime between ultrarelativistic and non-relativistic flow for gamma-ray burst afterglows. The hydrodynamics of spherically symmetric blast waves is numerically calculated using the AMRVAC adaptive mesh refinement code. Spectra and light curves are calculated using a separate radiation code that, for the first time, links a parametrization of the microphysics of shock acceleration, synchrotron self-absorption and electron cooling to a high-performance hydrodynamic simulation. For the dynamics, we find that the transition to the non-relativistic regime generally occurs later than expected, the Sedov-Taylor solution overpredicts the late-time blast wave radius and the analytical formula for the blast wave velocity from Huang, Dai & Lu overpredicts the late-time velocity by a factor of 4/3. Also, we find that the lab frame density directly behind the shock front divided by the fluid Lorentz factor squared remains very close to four times the unshocked density, while the effective adiabatic index of the shock changes from relativistic to non-relativistic. For the radiation, we find that the flux may differ up to an order of magnitude depending on the equation of state that is used for the fluid and that the counterjet leads to a clear rebrightening at late times for hard-edged jets. Simulating GRB 030329 using predictions for its physical parameters from the literature leads to spectra and light curves that may differ significantly from the actual data, emphasizing the need for very accurate modelling. Predicted light curves at low radio frequencies for a hard-edged jet model of GRB 030329 with opening angle 22° show typically two distinct peaks, due to the combined effect of jet break, non-relativistic break and counterjet. Spatially resolved afterglow images show a ring-like structure.

  17. Dissociative recombination studies in stationary and flowing afterglows

    NASA Astrophysics Data System (ADS)

    Skrzypkowski, Miroslaw Piotr

    2000-11-01

    The dissociative recombination of NH4+(NH 3)2,3 cluster-ions with electrons has been studied in a stationary afterglow experiment in which the electron temperature Te was elevated by radio- frequency heating from 300K up to 1000K. The recombination coefficients for the n = 2 and n = 3 cluster ions were found to be equal, α2 = α3 = (4.8 +/- 0.5) × 10-6cm3/s, and to vary with electron temperature as Te-0.65 . The known temperature dependence of the recombination coefficient of Ar2+ ions was remeasured to check the validity of the methods employed to calculate the electron-temperature scale in the experiment. A flowing afterglow/Langmuir probe (FALP) technique in conjunction with spatially resolved optical emission spectroscopy has been used to measure the absolute yield of radiative product states from ion-electron recombination. The technique was applied to the dissociative recombination of CO2 +, HCO+/COH+, HCO2 +, N2O+, and N2OH+/HN 2O+ ions with electrons at 300K. The vibrational distribution in CO(a3Π, v = 0-3) from CO2+ + e and in CO(a3Π, v = 0-4) from HCO+ + e was deduced. Contrary to expectations, no spectral features in the 550-750 region could be ascribed to the dissociative recombination in H3 +/e plasmas. FALP, coupled with spatially-resolved laser induced fluorescence (LIF), was also used in the studies of H- atom branching ratio from H3 + + e.

  18. Constraining chameleon field theories using the GammeV afterglow experiments

    NASA Astrophysics Data System (ADS)

    Upadhye, A.; Steffen, J. H.; Weltman, A.

    2010-01-01

    The GammeV experiment has constrained the couplings of chameleon scalar fields to matter and photons. Here, we present a detailed calculation of the chameleon afterglow rate underlying these constraints. The dependence of GammeV constraints on various assumptions in the calculation is studied. We discuss the GammeV-CHameleon Afterglow SEarch, a second-generation GammeV experiment, which will improve upon GammeV in several major ways. Using our calculation of the chameleon afterglow rate, we forecast model-independent constraints achievable by GammeV-CHameleon Afterglow SEarch. We then apply these constraints to a variety of chameleon models, including quartic chameleons and chameleon dark energy models. The new experiment will be able to probe a large region of parameter space that is beyond the reach of current tests, such as fifth force searches, constraints on the dimming of distant astrophysical objects, and bounds on the variation of the fine structure constant.

  19. Hidden in the light: Magnetically induced afterglow from trapped chameleon fields

    SciTech Connect

    Gies, Holger; Mota, David F.; Shaw, Douglas J.

    2008-01-15

    We propose an afterglow phenomenon as a unique trace of chameleon fields in optical experiments. The vacuum interaction of a laser pulse with a magnetic field can lead to a production and subsequent trapping of chameleons in the vacuum chamber, owing to their mass dependence on the ambient matter density. Magnetically induced reconversion of the trapped chameleons into photons creates an afterglow over macroscopic timescales that can conveniently be searched for by current optical experiments. We show that the chameleon parameter range accessible to available laboratory technology is comparable to scales familiar from astrophysical stellar energy-loss arguments. We analyze quantitatively the afterglow properties for various experimental scenarios and discuss the role of potential background and systematic effects. We conclude that afterglow searches represent an ideal tool to aim at the production and detection of cosmologically relevant scalar fields in the laboratory.

  20. Comment on 'Shock-wave-induced enhancement of optical emission in nitrogen afterglow plasma'

    SciTech Connect

    Naidis, G. V.

    2007-01-15

    Sieffert et al. [Phys. Rev. E 72, 066402 (2005)] have recently presented experimental results on optical emission enhancement at the front of shockwaves propagating in nitrogen afterglow. They claim that their results point to local heating of electrons at the shock front. In this Comment it is shown that the observed emission enhancement can be explained on the basis of a commonly accepted model of nitrogen discharge and afterglow, so that the use of unfounded assumption of local electron heating is not required.

  1. Influence of plasma diffusion losses on dust charge relaxation in discharge afterglow

    SciTech Connect

    Coueedel, L.; Mikikian, M.; Boufendi, L.

    2008-09-07

    The influence of diffusive losses on residual dust charge in a complex plasma afterglow has been investigated. The dust residual charges were simulated based on a model developed to describe complex plasma decay. The experimental and simulated data show that the transition from ambipolar to free diffusion in the decaying plasma plays a significant role in determining the residual dust particle charges. The presence of positively charged dust particles is explained by a broadening of the charge distribution function in the afterglow plasma.

  2. Escherichia coli morphological changes and lipid A removal induced by reduced pressure nitrogen afterglow exposure.

    PubMed

    Zerrouki, Hayat; Rizzati, Virginie; Bernis, Corinne; Nègre-Salvayre, Anne; Sarrette, Jean Philippe; Cousty, Sarah

    2015-01-01

    Lipid A is a major hydrophobic component of lipopolysaccharides (endotoxin) present in the membrane of most Gram-negative bacteria, and the major responsible for the bioactivity and toxicity of the endotoxin. Previous studies have demonstrated that the late afterglow region of flowing post-discharges at reduced pressure (1-20 Torr) can be used for the sterilization of surfaces and of the reusable medical instrumentation. In the present paper, we show that the antibacterial activity of a pure nitrogen afterglow can essentially be attributed to the large concentrations of nitrogen atoms present in the treatment area and not to the UV radiation of the afterglow. In parallel, the time variation of the inactivation efficiency quantified by the log reduction of the initial Escherichia coli (E. coli) population is correlated with morphologic changes observed on the bacteria by scanning electron microscopy (SEM) for increasing afterglow exposure times. The effect of the afterglow exposure is also studied on pure lipid A and on lipid A extracted from exposed E. coli bacteria. We report that more than 60% of lipid A (pure or bacteria-extracted) are lost with the used operating conditions (nitrogen flow QN2 = 1 standard liter per minute (slpm), pressure p = 5 Torr, microwave injected power PMW = 200 W, exposure time: 40 minutes). The afterglow exposure also results in a reduction of the lipid A proinflammatory activity, assessed by the net decrease of the redox-sensitive NFκB transcription factor nuclear translocation in murine aortic endothelial cells stimulated with control vs afterglow-treated (pure and extracted) lipid A. Altogether these results point out the ability of reduced pressure nitrogen afterglows to neutralize the cytotoxic components in Gram-negative bacteria.

  3. Escherichia coli Morphological Changes and Lipid A Removal Induced by Reduced Pressure Nitrogen Afterglow Exposure

    PubMed Central

    Zerrouki, Hayat; Rizzati, Virginie; Bernis, Corinne; Nègre-Salvayre, Anne; Sarrette, Jean Philippe; Cousty, Sarah

    2015-01-01

    Lipid A is a major hydrophobic component of lipopolysaccharides (endotoxin) present in the membrane of most Gram-negative bacteria, and the major responsible for the bioactivity and toxicity of the endotoxin. Previous studies have demonstrated that the late afterglow region of flowing post-discharges at reduced pressure (1-20 Torr) can be used for the sterilization of surfaces and of the reusable medical instrumentation. In the present paper, we show that the antibacterial activity of a pure nitrogen afterglow can essentially be attributed to the large concentrations of nitrogen atoms present in the treatment area and not to the UV radiation of the afterglow. In parallel, the time variation of the inactivation efficiency quantified by the log reduction of the initial Escherichia coli (E. coli) population is correlated with morphologic changes observed on the bacteria by scanning electron microscopy (SEM) for increasing afterglow exposure times. The effect of the afterglow exposure is also studied on pure lipid A and on lipid A extracted from exposed E. coli bacteria. We report that more than 60% of lipid A (pure or bacteria-extracted) are lost with the used operating conditions (nitrogen flow QN2 = 1 standard liter per minute (slpm), pressure p = 5 Torr, microwave injected power PMW = 200 W, exposure time: 40 minutes). The afterglow exposure also results in a reduction of the lipid A proinflammatory activity, assessed by the net decrease of the redox-sensitive NFκB transcription factor nuclear translocation in murine aortic endothelial cells stimulated with control vs afterglow-treated (pure and extracted) lipid A. Altogether these results point out the ability of reduced pressure nitrogen afterglows to neutralize the cytotoxic components in Gram-negative bacteria. PMID:25837580

  4. GRB 110715A: the peculiar multiwavelength evolution of the first afterglow detected by ALMA

    NASA Astrophysics Data System (ADS)

    Sánchez-Ramírez, R.; Hancock, P. J.; Jóhannesson, G.; Murphy, Tara; de Ugarte Postigo, A.; Gorosabel, J.; Kann, D. A.; Krühler, T.; Oates, S. R.; Japelj, J.; Thöne, C. C.; Lundgren, A.; Perley, D. A.; Malesani, D.; de Gregorio Monsalvo, I.; Castro-Tirado, A. J.; D'Elia, V.; Fynbo, J. P. U.; Garcia-Appadoo, D.; Goldoni, P.; Greiner, J.; Hu, Y.-D.; Jelínek, M.; Jeong, S.; Kamble, A.; Klose, S.; Kuin, N. P. M.; Llorente, A.; Martín, S.; Nicuesa Guelbenzu, A.; Rossi, A.; Schady, P.; Sparre, M.; Sudilovsky, V.; Tello, J. C.; Updike, A.; Wiersema, K.; Zhang, B.-B.

    2017-02-01

    We present the extensive follow-up campaign on the afterglow of GRB 110715A at 17 different wavelengths, from X-ray to radio bands, starting 81 s after the burst and extending up to 74 d later. We performed for the first time a GRB afterglow observation with the ALMA observatory. We find that the afterglow of GRB 110715A is very bright at optical and radio wavelengths. We use the optical and near-infrared spectroscopy to provide further information about the progenitor's environment and its host galaxy. The spectrum shows weak absorption features at a redshift z = 0.8225, which reveal a host-galaxy environment with low ionization, column density, and dynamical activity. Late deep imaging shows a very faint galaxy, consistent with the spectroscopic results. The broad-band afterglow emission is modelled with synchrotron radiation using a numerical algorithm and we determine the best-fitting parameters using Bayesian inference in order to constrain the physical parameters of the jet and the medium in which the relativistic shock propagates. We fitted our data with a variety of models, including different density profiles and energy injections. Although the general behaviour can be roughly described by these models, none of them are able to fully explain all data points simultaneously. GRB 110715A shows the complexity of reproducing extensive multiwavelength broad-band afterglow observations, and the need of good sampling in wavelength and time and more complex models to accurately constrain the physics of GRB afterglows.

  5. The Nature of the Most Extreme Cosmic Explosions: Broadband Studies of Fermi LAT GRB Afterglows

    NASA Astrophysics Data System (ADS)

    Kidd, Lauren; Troja, E.

    2014-01-01

    In the five years since its launch, the Fermi Large Area Telescope (LAT) has revealed a population of gamma-ray bursts (GRBs) that are among the most energetic explosions ever observed. While typical GRB afterglows are observed from radio to X-rays, afterglows of Fermi LAT GRBs are detected up to GeV energies, challenging our understanding of GRB emission mechanisms and central engines. There are now a significant number of LAT-detected GRBs with multi-wavelength afterglow data and measured redshifts that allow us to investigate potential correlations between this high-energy (> 100 MeV) emission and the afterglow parameters and determine if any particular conditions (e.g., weak magnetic field or low density medium) must be met by the progenitor system in order to generate the bright GeV emission. We developed an afterglow fitting code to model and fit the broadband afterglow data in counts space, allowing us to directly test the model predictions on the observed data. The uncertainties in our results were derived using a Markov Chain Monte Carlo analysis, which allows us to uncover degeneracies between the physical parameters of the explosion. Here we present the preliminary results of our study of the population of Fermi LAT-detected GRBs.

  6. CALORIMETRY OF GRB 030329: SIMULTANEOUS MODEL FITTING TO THE BROADBAND RADIO AFTERGLOW AND THE OBSERVED IMAGE EXPANSION RATE

    SciTech Connect

    Mesler, Robert A.; Pihlstroem, Ylva M.

    2013-09-01

    We perform calorimetry on the bright gamma-ray burst GRB 030329 by fitting simultaneously the broadband radio afterglow and the observed afterglow image size to a semi-analytic MHD and afterglow emission model. Our semi-analytic method is valid in both the relativistic and non-relativistic regimes, and incorporates a model of the interstellar scintillation that substantially effects the broadband afterglow below 10 GHz. The model is fitted to archival measurements of the afterglow flux from 1 day to 8.3 yr after the burst. Values for the initial burst parameters are determined and the nature of the circumburst medium is explored. Additionally, direct measurements of the lateral expansion rate of the radio afterglow image size allow us to estimate the initial Lorentz factor of the jet.

  7. Seven-year Collection of Well-monitored Fermi-LAT Gamma-Ray Burst Afterglows

    NASA Astrophysics Data System (ADS)

    Panaitescu, A.

    2017-03-01

    We present the light curves and spectra of 24 afterglows that have been monitored by Fermi-LAT at 0.1–100 GeV over more than a decade. All light curves (except 130427) are consistent with a single power law starting from their peaks, which occur in most cases before the burst end. The light curves display a brightness–decay rate correlation, with all but one (130427) of the bright afterglows decaying faster than the dimmer afterglows. We attribute this dichotomy to the quick deposition of relativistic ejecta energy in the external shock for the brighter/faster-decaying afterglows and to an extended energy injection in the afterglow shock for the dimmer/slower-decaying light curves. The spectra of six afterglows (090328, 100414, 110721, 110731, 130427, 140619B) indicate the existence of a harder component above a spectral dip or ankle at energies of 0.3–3 GeV, offering evidence for inverse-Compton emission at higher energies and suggesting that the harder power-law spectra of five other LAT afterglows (130327B, 131231, 150523, 150627, 160509) could also be inverse-Compton, while the remaining, softer LAT afterglows should be synchrotron emission. Marginal evidence for a spectral break and softening at higher energies is found for two afterglows (090902B and 090926).

  8. DIVERSITY OF SHORT GAMMA-RAY BURST AFTERGLOWS FROM COMPACT BINARY MERGERS HOSTING PULSARS

    SciTech Connect

    Holcomb, Cole; Ramirez-Ruiz, Enrico; De Colle, Fabio; Montes, Gabriela

    2014-07-20

    Short-duration gamma-ray bursts (sGRBs) are widely believed to result from the mergers of compact binaries. This model predicts an afterglow that bears the characteristic signatures of a constant, low-density medium, including a smooth prompt-afterglow transition, and a simple temporal evolution. However, these expectations are in conflict with observations for a non-negligible fraction of sGRB afterglows. In particular, the onset of the afterglow phase for some of these events appears to be delayed and, in addition, a few of them exhibit late-time rapid fading in their light curves. We show that these peculiar observations can be explained independently of ongoing central engine activity if some sGRB progenitors are compact binaries hosting at least one pulsar. The Poynting flux emanating from the pulsar companion can excavate a bow-shock cavity surrounding the binary. If this cavity is larger than the shock deceleration length scale in the undisturbed interstellar medium, then the onset of the afterglow will be delayed. Should the deceleration occur entirely within the swept-up thin shell, a rapid fade in the light curve will ensue. We identify two types of pulsar that can achieve the conditions necessary for altering the afterglow: low-field, long-lived pulsars, and high-field pulsars. We find that a sizable fraction (≈20%-50%) of low-field pulsars are likely to reside in neutron star binaries based on observations, while their high-field counterparts are not. Hydrodynamical calculations motivated by this model are shown to be in good agreement with observations of sGRB afterglow light curves.

  9. Modeling Extragalactic Extinction through Gamma-Ray Burst Afterglows

    NASA Astrophysics Data System (ADS)

    Zonca, Alberto; Cecchi-Pestellini, Cesare; Mulas, Giacomo; Casu, Silvia; Aresu, Giambattista

    2016-09-01

    We analyze extragalactic extinction profiles derived through gamma-ray burst afterglows, using a dust model specifically constructed on the assumption that dust grains are not immutable but respond, time-dependently, to the local physics. Such a model includes core-mantle spherical particles of mixed chemical composition (silicate core, sp2, and sp3 carbonaceous layers), and an additional molecular component in the form of free-flying polycyclic aromatic hydrocarbons. We fit most of the observed extinction profiles. Failures occur for lines of sight, presenting remarkable rises blueward of the bump. We find a tendency for the carbon chemical structure to become more aliphatic with the galactic activity, and to some extent with increasing redshifts. Moreover, the contribution of the molecular component to the total extinction is more important in younger objects. The results of the fitting procedure (either successes and failures) may be naturally interpreted through an evolutionary prescription based on the carbon cycle in the interstellar medium of galaxies.

  10. From Engine to Afterglow: Collapsars Naturally Produce Top-heavy Jets and Early-time Plateaus in Gamma-Ray Burst Afterglows

    NASA Astrophysics Data System (ADS)

    Duffell, Paul C.; MacFadyen, Andrew I.

    2015-06-01

    We demonstrate that the steep decay and long plateau in the early phases of gamma-ray burst X-ray afterglows are naturally produced in the collapsar model, by a means ultimately related to the dynamics of relativistic jet propagation through a massive star. We present two-dimensional axisymmetric hydrodynamical simulations that start from a collapsar engine and evolve all the way through the late afterglow phase. The resultant outflow includes a jet core that is highly relativistic after breaking out of the star, but becomes baryon loaded after colliding with a massive outer shell, corresponding to mass from the stellar atmosphere of the progenitor star which became trapped in front of the jet core at breakout. The prompt emission produced before or during this collision would then have the signature of a high Lorentz factor jet, but the afterglow is produced by the amalgamated post-collision ejecta that has more inertia than the original highly relativistic jet core and thus has a delayed deceleration. This naturally explains the early light curve behavior discovered by Swift, including a steep decay and a long plateau, without invoking late-time energy injection from the central engine. The numerical simulation is performed continuously from engine to afterglow, covering a dynamic range of over 10 orders of magnitude in radius. Light curves calculated from the numerical output demonstrate that this mechanism reproduces basic features seen in early afterglow data. Initial steep decays are produced by internal shocks, and the plateau corresponds to the coasting phase of the outflow.

  11. FROM ENGINE TO AFTERGLOW: COLLAPSARS NATURALLY PRODUCE TOP-HEAVY JETS AND EARLY-TIME PLATEAUS IN GAMMA-RAY BURST AFTERGLOWS

    SciTech Connect

    Duffell, Paul C.; MacFadyen, Andrew I. E-mail: macfadyen@nyu.edu

    2015-06-20

    We demonstrate that the steep decay and long plateau in the early phases of gamma-ray burst X-ray afterglows are naturally produced in the collapsar model, by a means ultimately related to the dynamics of relativistic jet propagation through a massive star. We present two-dimensional axisymmetric hydrodynamical simulations that start from a collapsar engine and evolve all the way through the late afterglow phase. The resultant outflow includes a jet core that is highly relativistic after breaking out of the star, but becomes baryon loaded after colliding with a massive outer shell, corresponding to mass from the stellar atmosphere of the progenitor star which became trapped in front of the jet core at breakout. The prompt emission produced before or during this collision would then have the signature of a high Lorentz factor jet, but the afterglow is produced by the amalgamated post-collision ejecta that has more inertia than the original highly relativistic jet core and thus has a delayed deceleration. This naturally explains the early light curve behavior discovered by Swift, including a steep decay and a long plateau, without invoking late-time energy injection from the central engine. The numerical simulation is performed continuously from engine to afterglow, covering a dynamic range of over 10 orders of magnitude in radius. Light curves calculated from the numerical output demonstrate that this mechanism reproduces basic features seen in early afterglow data. Initial steep decays are produced by internal shocks, and the plateau corresponds to the coasting phase of the outflow.

  12. Afterglow of a microwave microstrip plasma as an ion source for mass spectrometry

    NASA Astrophysics Data System (ADS)

    Pfeuffer, Kevin P.; White, Allen; Broekaert, José A. C.; Hieftje, Gary M.

    2015-01-01

    A microwave-induced plasma that was previously used for optical emission spectrometry has been repurposed as an afterglow ion source for mass spectrometry. This compact microwave discharge, termed the microstrip plasma (MSP), is operated at 20-50 W and 2.45 GHz in helium at a flow of 300 mL/min. The primary background ions present in the afterglow are ionized and protonated water clusters. An exponential dilution chamber was used to introduce volatile organic compounds into the MSP afterglow and yielded limits of detection in the 40 ppb to 7 ppm range (v/v). A hydride-generation system was also utilized for detection of volatile hydride-forming elements (arsenic, antimony, tin) in the afterglow and produced limits of detection in the 10-100 ppb range in solution. The MSP afterglow was found capable of desorption and ionization of analyte species directly from a solid substrate, suggesting its use as an ion source for ambient desorption/ionization mass spectrometry.

  13. Energy input and response from prompt and early optical afterglow emission in gamma-ray bursts.

    PubMed

    Vestrand, W T; Wren, J A; Wozniak, P R; Aptekar, R; Golentskii, S; Pal'shin, V; Sakamoto, T; White, R R; Evans, S; Casperson, D; Fenimore, E

    2006-07-13

    The taxonomy of optical emission detected during the critical first few minutes after the onset of a gamma-ray burst (GRB) defines two broad classes: prompt optical emission correlated with prompt gamma-ray emission, and early optical afterglow emission uncorrelated with the gamma-ray emission. The standard theoretical interpretation attributes prompt emission to internal shocks in the ultra-relativistic outflow generated by the internal engine; early afterglow emission is attributed to shocks generated by interaction with the surrounding medium. Here we report on observations of a bright GRB that, for the first time, clearly show the temporal relationship and relative strength of the two optical components. The observations indicate that early afterglow emission can be understood as reverberation of the energy input measured by prompt emission. Measurements of the early afterglow reverberations therefore probe the structure of the environment around the burst, whereas the subsequent response to late-time impulsive energy releases reveals how earlier flaring episodes have altered the jet and environment parameters. Many GRBs are generated by the death of massive stars that were born and died before the Universe was ten per cent of its current age, so GRB afterglow reverberations provide clues about the environments around some of the first stars.

  14. The late X-ray afterglow of gamma-ray bursts.

    PubMed

    Willingale, Richard; O'Brien, Paul T

    2007-05-15

    We have developed a functional fit which can be used to represent the entire temporal decay of the X-ray afterglow of gamma-ray bursts (GRBs). The fit delineates and parameterizes well-defined phases for the decay: the prompt emission; an initial steep decay; a shallow plateau phase; and finally, a powerlaw afterglow. For 20% of GRBs, the plateau phase is weak, or not seen, and the initial powerlaw decay becomes the final afterglow.We compare the temporal decay parameters and X-ray spectral indices for 107 GRBs discovered by Swift with the expectations of the standard fireball model including a search for possible jet breaks. For approximately 50% of GRBs, the observed afterglow is in accord with the model, but for the rest the temporal and spectral properties are not as expected. We identify a few possible jet breaks, but there are many examples where such breaks are predicted but are absent. We also find that the start time of the final afterglow decay, Ta, is associated with the peak of the prompt gamma-ray emission spectrum, Epeak, just as optical jet-break times, tj, are associated with Epeak in the Ghirlanda relation.

  15. Constraints on an Optical Afterglow and on Supernova Light Following the Short Burst GRB 050813

    NASA Technical Reports Server (NTRS)

    Ferrero, P.; Sanchez, S. F.; Kann, D. A.; Klose, S.; Greiner, J.; Gorosabel, J.; Hartmann, D. H.; Henden, A. A.; Moller, P.; Palazzi, E.; Rau, A.; Stecklum, B.; Castro-Tirado, A. J.; Fynbok J. P. U.; Hjorth, J.; Jakobsson, P.; Kouveliotou, C.; Masetti, N.; Pian, E.; Tanvir, N. R.; Wijers, R. A. M. J.

    2006-01-01

    We report early follow-up observations of the error box of the short burst 050813 using the telescopes at Calar Alto and at Observatorio Sierra Nevada (OSN), followed by deep VLT/FORS2 I-band observations obtained under very good seeing conditions 5.7 and 11.7 days after the event. No evidence for a GRB afterglow was found in our Calar Alto and OSN data, no rising supernova component was detected in our FORS2 images. A potential host galaxy can be identified in our FORS2 images, even though we cannot state with certainty its association with GRB 050813. IN any case, the optical afterglow of GRB 050813 was very faint, well in agreement with what is known so far about the optical properties of afterglows of short bursts. We conclude that all optical data are not in conflict with the interpretation that GRB 050813 was a short burst.

  16. Machine Learning Search for Gamma-Ray Burst Afterglows in Optical Images

    NASA Astrophysics Data System (ADS)

    Topinka, M.

    2016-06-01

    Thanks to the advances in robotic telescopes, time domain astronomy leads to a large number of transient events detected in images every night. Data mining and machine learning tools used for object classification are presented. The goal is to automatically classify transient events for both further follow-up by a larger telescope and for statistical studies of transient events. Special attention is given to the identification of gamma-ray burst afterglows. Machine learning techniques are used to identify GROND gamma-ray burst afterglow among the astrophysical objects present in the SDSS archival images based on the g'-r', r'-i' and i'-z' color indices. The performance of the support vector machine, random forest and neural network algorithms is compared. A joint meta-classifier, built on top of the individual classifiers, can identify GRB afterglows with the overall accuracy of ≳ 90%.

  17. An on-line Langmuir probe technique for the study of afterglow plasmas

    NASA Astrophysics Data System (ADS)

    Spanel, Patrik

    1995-11-01

    A new analytical technique has been developed to determine from Langmuir probe characteristics the electron number densities, electron energy distribution functions and electron temperatures in thermal and near-thermal afterglow plasmas. This technique utilises a standard personal computer equipped with a simple 12-bit analogue/digital and digital/analogue converters coupled to the Langmuire probe via a specially designed differential amplifier. The energy distribution functions are obtained by numerical differentiation of the probe characteristics using a fast noise-suppressing numerical technique, the mathematical principles of which are discussed in some detail. Some sample data, which have been obtained in truly thermalised helium flowing afterglows and in argon flowing afterglow at elevated electron temperatures, are presented to demonstrate the value of this new analytical technique.

  18. Controlled growth of copper oxide nanostructures by atmospheric pressure micro-afterglow

    NASA Astrophysics Data System (ADS)

    Altaweel, A.; Filipič, G.; Gries, T.; Belmonte, T.

    2014-12-01

    A large variety of copper oxide nanostructures encompassing nanodots, nanowires and nanowalls, sometimes organized in "cabbage-like" architectures, are grown locally by direct oxidation of copper thin films using the micro-afterglow of an Ar-O2 microwave plasma operating at atmospheric pressure. Morphology, structure and composition of the oxidized copper thin films are characterized by X-ray diffraction, secondary ion mass spectrometry and scanning electron microscopy. The concentric areas where each kind of nanostructures is found are defined by both their radial position with respect to the afterglow centre and by experimental conditions. A growth mechanism is proposed, based on stress-induced outward migration of copper ions. The development of stress gradients is caused by the formation of a copper oxide scale layer. If copper oxide nanowires can be grown as in thermal oxidation processes, micro-afterglow conditions offer novel nanostructures and nano-architectures.

  19. X-ray excited ZnS:Cu,Co afterglow nanoparticles for photodynamic activation

    NASA Astrophysics Data System (ADS)

    Ma, Lun; Zou, Xiaoju; Bui, Brian; Chen, Wei; Song, Kwang Hyun; Solberg, Timothy

    2014-07-01

    Copper and cobalt co-doped ZnS (ZnS:Cu,Co) afterglow nanoparticles were conjugated to photosensitizer tetrabromorhodamine-123 (TBrRh123) and efficient energy transfer from the nanoparticles to TBrRh123 was observed. In addition to their X-ray excited luminescence, the ZnS:Cu,Co nanoparticles also show long lasting afterglow, which continuously serve as a light source for photodynamic therapy (PDT) activation. Compared to TBrRh123 or ZnS:Cu,Co alone, the ZnS:Cu,Co-TBrRh123 conjugates show low dark toxicity but high X-ray induced toxicity to human prostate cancer cells. The results indicate that the ZnS:Cu,Co afterglow nanoparticles have a good potential for PDT activation.

  20. THE AFTERGLOW AND ENVIRONMENT OF THE SHORT GRB 111117A

    SciTech Connect

    Margutti, R.; Berger, E.; Fong, W.; Zauderer, B. A.; Soderberg, A. M.; Milisavljevic, D.; Sanders, N.; Cenko, S. B.; Greiner, J.; Cucchiara, A.

    2012-09-01

    We present multi-wavelength observations of the afterglow of the short GRB 111117A, and follow-up observations of its host galaxy. From rapid optical and radio observations, we place limits of r {approx}> 25.5 mag at {delta}t Almost-Equal-To 0.55 days and F{sub {nu}}(5.8 GHz) {approx}< 18 {mu}Jy at {delta}t Almost-Equal-To 0.50 days, respectively. However, using a Chandra observation at {delta}t Almost-Equal-To 3.0 days we locate the absolute position of the X-ray afterglow to an accuracy of 0.''22 (1{sigma}), a factor of about six times better than the Swift/XRT position. This allows us to robustly identify the host galaxy and to locate the burst at a projected offset of 1.''25 {+-} 0.''20 from the host centroid. Using optical and near-IR observations of the host galaxy we determine a photometric redshift of z = 1.3{sup +0.3}{sub -0.2}, one of the highest for any short gamma-ray burst (GRB), leading to a projected physical offset for the burst of 10.5 {+-} 1.7 kpc, typical of previous short GRBs. At this redshift, the isotropic {gamma}-ray energy is E{sub {gamma},iso} Almost-Equal-To 3.0 Multiplication-Sign 10{sup 51} erg (rest-frame 23-2300 keV) with a peak energy of E{sub pk} Almost-Equal-To 850-2300 keV (rest-frame). In conjunction with the isotropic X-ray energy, GRB 111117A appears to follow our recently reported E{sub x,iso}-E{sub {gamma},iso}-E{sub pk} universal scaling. Using the X-ray data along with the optical and radio non-detections, we find that for a blastwave kinetic energy of E{sub K,iso} Almost-Equal-To E{sub {gamma},iso} erg, the circumburst density is n{sub 0} Almost-Equal-To 3 Multiplication-Sign 10{sup -4} - 1 cm{sup -3} (for a range of {epsilon}{sub B} = 0.001-0.1). Similarly, from the non-detection of a break in the X-ray light curve at {delta}t {approx}< 3 days, we infer a minimum opening angle for the outflow of {theta}{sub j} {approx}> 3-10 Degree-Sign (depending on the circumburst density). We conclude that Chandra observations of short

  1. Degravitation, inflation and the cosmological constant as an afterglow

    NASA Astrophysics Data System (ADS)

    Patil, Subodh P.

    2009-01-01

    In this report, we adopt the phenomenological approach of taking the degravitation paradigm seriously as a consistent modification of gravity in the IR, and investigate its consequences for various cosmological situations. We motivate degravitation — where Netwon's constant is promoted to a scale dependent filter function — as arising from either a small (resonant) mass for the graviton, or as an effect in semi-classical gravity. After addressing how the Bianchi identities are to be satisfied in such a set up, we turn our attention towards the cosmological consequences of degravitation. By considering the example filter function corresponding to a resonantly massive graviton (with a filter scale larger than the present horizon scale), we show that slow roll inflation, hybrid inflation and old inflation remain quantitatively unchanged. We also find that the degravitation mechanism inherits a memory of past energy densities in the present epoch in such a way that is likely significant for present cosmological evolution. For example, if the universe underwent inflation in the past due to it having tunneled out of some false vacuum, we find that degravitation implies a remnant `afterglow' cosmological constant, whose scale immediately afterwards is parametrically suppressed by the filter scale (L) in Planck units Λ ~ l2pl/L2. We discuss circumstances through which this scenario reasonably yields the presently observed value for Λ ~ O(10-120). We also find that in a universe still currently trapped in some false vacuum state, resonance graviton models of degravitation only degravitate initially Planck or GUT scale energy densities down to the presently observed value over timescales comparable to the filter scale. We argue that different functional forms for the filter function will yield similar conclusions. In this way, we argue that although the degravitation models we study have the potential to explain why the cosmological constant is not large in addition to

  2. Recombination of H3+ Ions with Electrons in Afterglow Plasmas

    NASA Astrophysics Data System (ADS)

    Johnsen, Rainer; Glosik, Juraj; Dohnal, Petr; Rubovic, Peter; Kalosi, Abel; Plasil, Radek

    2015-09-01

    Our past and ongoing flowing and stationary afterglow experiments at temperatures from 60-340 K have resulted in a more complete picture of the plasma recombination of H3+ ions: (1) Optical absorption studies indicate that at T = 300 K both para and ortho H3+ ions recombine with nearly the same binary coefficient αbin ~ 0.6 × 10-7 cm3/s. However, at T = 60 K para H3+ recombines faster by about a factor of ~10 than does ortho H3+.(2) Earlier discrepancies between data obtained in plasmas and those obtained in merged-beam or storage-rings have been traced to ternary recombination due to ambient helium atoms and/or hydrogen molecules. Ternary recombination of H3+ due to He or H2 is more efficient by factors ~ 102 or 105, respectively, than expected from the theoretical model of Bates and Khare for atomic ions. (3) The ternary processes enhance recombination at low third-body densities (1017 cm-3) but then level off (``saturate'') when their contribution approaches ~ 1.5 × 10-7 cm3/s. This saturation can lead to the false inference that the overall recombination is binary, resulting in a recombination coefficient that is about 3 times too large. (4) A tentative complex model has been developed that rationalizes the observed effects. This work was partly supported by Czech Science Foundation projects GACR 14-14649P and GACR 15-15077S and by Charles University in Prague projects GAUK 692214, GAUK 572214, UNCE 204020/2012 and SVV 260.

  3. The γ-ray afterglows of tidal disruption events.

    PubMed

    Chen, Xian; Gómez-Vargas, Germán Arturo; Guillochon, James

    2016-05-21

    A star wandering too close to a supermassive black hole (SMBH) will be tidally disrupted. Previous studies of such 'tidal disruption event' (TDE) mostly focus on the stellar debris that are bound to the system, because they give rise to luminous flares. On the other hand, half of the stellar debris in principle are unbound and can stream to a great distance, but so far there is no clear evidence that this 'unbound debris stream' (UDS) exists. Motivated by the fact that the circum-nuclear region around SMBHs is usually filled with dense molecular clouds (MCs), here we investigate the observational signatures resulting from the collision between an UDS and an MC, which is likely to happen hundreds of years after a TDE. We focus on γ-ray emission (0.1-10(5) GeV), which comes from the encounter of shock-accelerated cosmic rays with background protons and, more importantly, is not subject to extinction. We show that because of the high proton density inside an MC, the peak γ-ray luminosity, about 10(39) erg s(-1), is at least 100 times greater than that in the case without an MC (only with a smooth interstellar medium). The luminosity decays on a time-scale of decades, depending on the distance of the MC, and about a dozen of these 'TDE afterglows' could be detected within a distance of about 16 Mpc by the future Cherenkov Telescope Array. Without careful discrimination, these sources potentially could contaminate the searches for starburst galaxies, galactic nuclei containing millisecond pulsars or dark matter annihilation signals.

  4. PROBING EXTRAGALACTIC DUST THROUGH NEARBY GAMMA-RAY BURST AFTERGLOWS

    SciTech Connect

    Liang, S. L.; Li Aigen E-mail: lia@missouri.ed

    2010-02-10

    The quantities and wavelength dependencies of the dust extinction along the lines of sight toward 33 nearby gamma-ray bursts (GRBs) with redshifts z < 2 are derived from fitting their afterglow spectral energy distributions. Unlike previous studies which often assume a specific extinction law like that of the Milky Way (MW) and the Large and Small Magellanic Clouds (LMC/SMC), our approach-we call it the 'Drude' approach-is more flexible in determining the true wavelength dependence of the extinction (while the shape of the extinction curve inferred from that relying on a priori assumption of a template extinction law is, of course, fixed). The extinction curves deduced from the Drude approach display a wide diversity of shapes, ranging from relatively flat curves to curves which are featureless and steeply rise toward the far-ultraviolet, and from curves just like that of the MW, LMC, and SMC to curves resembling that of the MW and LMC but lacking the 2175 A bump. The visual extinction A{sub V} derived from the Drude approach is generally larger by a factor of {approx}2-5 than that inferred by assuming a SMC-type template extinction law. Consistent with previous studies, the extinction-to-gas ratio is mostly smaller than that of the MW, and does not seem to correlate with the shape of the extinction curve. It is shown that the standard silicate-graphite interstellar grain model closely reproduces the extinction curves of all 33 GRBs host galaxies. For these 33 bursts at z < 2, we find no evidence for the evolution of the dust extinction, dust sizes, and relative abundances of silicate to graphite on redshifts.

  5. GRB Orphan Afterglows in Present and Future Radio Transient Surveys

    NASA Astrophysics Data System (ADS)

    Ghirlanda, G.; Burlon, D.; Ghisellini, G.; Salvaterra, R.; Bernardini, M. G.; Campana, S.; Covino, S.; D'Avanzo, P.; D'Elia, V.; Melandri, A.; Murphy, T.; Nava, L.; Vergani, S. D.; Tagliaferri, G.

    2014-05-01

    Orphan Afterglows (OA) are slow transients produced by Gamma Ray Bursts seen off-axis that become visible on timescales of days/years at optical/NIR and radio frequencies, when the prompt emission at high energies (X and γ rays) has already ceased. Given the typically estimated jet opening angle of GRBs θjet ~ 3°, for each burst pointing to the Earth there should be a factor ~ 700 more GRBs pointing in other directions. Despite this, no secure OAs have been detected so far. Through a population synthesis code we study the emission properties of the population of OA at radio frequencies. OAs reach their emission peak on year-timescales and they last for a comparable amount of time. The typical peak fluxes (which depend on the observing frequency) are of few μJy in the radio band with only a few OA reaching the mJy level. These values are consistent with the upper limits on the radio flux of SN Ib/c observed at late times. We find that the OA radio number count distribution has a typical slope - 1.7 at high fluxes and a flatter ( - 0.4) slope at low fluxes with a break at a frequency-dependent flux. Our predictions of the OA rates are consistent with the (upper) limits of recent radio surveys and archive searches for radio transients. Future radio surveys like VAST/ASKAP at 1.4 GHz should detect ~ 3 × 10- 3 OA deg- 2 yr- 1, MeerKAT and EVLA at 8.4 GHz should see ~ 3 × 10- 1 OA deg- 2 yr- 1. The SKA, reaching the μJy flux limit, could see up to ~ 0.2 - 1.5 OA deg- 2 yr- 1. These rates also depend on the duration of the OA above a certain flux limit and we discuss this effect with respect to the survey cadence.

  6. A unifying view of gamma-ray burst afterglows

    NASA Astrophysics Data System (ADS)

    Ghisellini, G.; Nardini, M.; Ghirlanda, G.; Celotti, A.

    2009-02-01

    We selected a sample of 33 gamma-ray bursts detected by Swift, with known redshift and optical extinction at the host frame. For these, we constructed the de-absorbed and K-corrected X-ray and optical rest-frame light curves. These are modelled as the sum of two components: emission from the forward shock due to the interaction of a fireball with the circumburst medium and an additional component, treated in a completely phenomenological way. The latter can be identified, among other possibilities, as a `late prompt' emission produced by a long-lived central engine with mechanisms similar to those responsible for the production of the `standard' early prompt radiation. Apart from flares or re-brightenings, that we do not model, we find a good agreement with the data, despite of their complexity and diversity. Although based, in part, on a phenomenological model with a relatively large number of free parameters, we believe that our findings are a first step towards the construction of a more physical scenario. Our approach allows us to interpret the behaviour of the optical and X-ray afterglows in a coherent way, by a relatively simple scenario. Within this context, it is possible to explain why sometimes no jet break is observed; why, even if a jet break is observed, it is often chromatic and why the steepening after the jet break time is often shallower than predicted. Finally, the decay slope of the late prompt emission after the shallow phase is found to be remarkably similar to the time profile expected by the accretion rate of fall-back material (i.e. ~ t-5/3), suggesting that this can be the reason why the central engine can be active for a long time.

  7. The γ-ray afterglows of tidal disruption events

    NASA Astrophysics Data System (ADS)

    Chen, Xian; Gómez-Vargas, Germán Arturo; Guillochon, James

    2016-05-01

    A star wandering too close to a supermassive black hole (SMBH) will be tidally disrupted. Previous studies of such `tidal disruption event' (TDE) mostly focus on the stellar debris that are bound to the system, because they give rise to luminous flares. On the other hand, half of the stellar debris in principle are unbound and can stream to a great distance, but so far there is no clear evidence that this `unbound debris stream' (UDS) exists. Motivated by the fact that the circum-nuclear region around SMBHs is usually filled with dense molecular clouds (MCs), here we investigate the observational signatures resulting from the collision between an UDS and an MC, which is likely to happen hundreds of years after a TDE. We focus on γ-ray emission (0.1-105 GeV), which comes from the encounter of shock-accelerated cosmic rays with background protons and, more importantly, is not subject to extinction. We show that because of the high proton density inside an MC, the peak γ-ray luminosity, about 1039 erg s-1, is at least 100 times greater than that in the case without an MC (only with a smooth interstellar medium). The luminosity decays on a time-scale of decades, depending on the distance of the MC, and about a dozen of these `TDE afterglows' could be detected within a distance of about 16 Mpc by the future Cherenkov Telescope Array. Without careful discrimination, these sources potentially could contaminate the searches for starburst galaxies, galactic nuclei containing millisecond pulsars or dark matter annihilation signals.

  8. Advances in flowing afterglow and selected-ion flow tube techniques

    NASA Astrophysics Data System (ADS)

    Squires, Robert R.

    1992-09-01

    New developments in flowing afterglow and selected-ion flow tube (SIFT) techniques are briefly reviewed. Particular emphasis is given to the new chemical and physical information that can be obtained with use of the tandem flowing afterglow-triple quadrupole apparatus developed in the author's laboratory. Several outstanding recent achievements in the design and utilization of flowing afterglow and SIFT instruments in other laboratories are briefly highlighted that illustrate the power and flexibility of flow-tube-based methods. These include isotope tracer experiments with the tandem flowing afterglow-SIFT instrument in Boulder, studies of large molecular cluster ions with the variable temperature facility at Penn State, and gas-phase metal ion reactions with the laser ablation/fast flow reactor in Madison. Recent applications of the flowing afterglow-triple quadrupole instrument in our laboratory have made use of collision-induced dissociation (CID) as a tool for synthesizing novel ions and for obtaining new thermo-chemical information from threshold energy measurements. Collision-induced decar☐ylation of organic car☐ylate ions provides access to a variety of unusual and highly basic carbanions that cannot be generated with conventional ion sources. The formation and properties of saturated alkyl ions and studies of gas-phase reactions of the methyl anion are briefly described. We have developed a new method for carrying out "preparative CID" in a flowing afterglow with use of a mini-drift tube; some recent applications of this new ion source are presented. Measurement of CID thresholds for simple cleavage reactions of thermalized ions can provide accurate measures of bond strengths, gas-phase acidities and basicities, and heats of formation for ions and reactive neutral species. Applications of this approach in the thermochemical characterization of carbenes, benzynes and biradicals are described. Future prospects for the continued development of flow

  9. Observation on long afterglow of Tb{sup 3+} in CaWO{sub 4}

    SciTech Connect

    Wu, Haoyi; Hu, Yihua; Kang, Fengwen; Chen, Li; Wang, Xiaojuan; Ju, Guifang; Mu, Zhongfei

    2011-12-15

    Graphical abstract: The afterglow of Tb{sup 3+} is observed in CaWO{sub 4} matrix. The main emission of the afterglow is ascribed to the {sup 5}D{sub 4} {yields} {sup 7}F{sub 5} and {sup 5}D{sub 4} {yields} {sup 7}F{sub 6}. Emission due to {sup 5}D{sub 3} {yields} {sup 7}F{sub 4} and {sup 5}D{sub 3} {yields} {sup 7}F{sub 5} is weak. The cross-relaxation dominate the afterglow emission and it enhances the transition from {sup 5}D{sub 4} whereas from {sup 5}D{sub 3}. Highlights: Black-Right-Pointing-Pointer A green long afterglow is observed from Tb{sup 3+} in CaWO{sub 4} matrix. Black-Right-Pointing-Pointer Two traps which may have a strong influence on the afterglow properties are revealed by TL. Black-Right-Pointing-Pointer A mechanism model based on energy transfer from WO{sub 4}{sup 2-} group to Tb{sup 3+} followed by cross-relaxation is proposed. -- Abstract: The Tb{sup 3+} doped CaWO{sub 4} phosphors are synthesized via high temperature solid state reaction. The X-ray diffraction shows that small amount of Tb{sup 3+} does not have a significant influence on the structure of CaWO{sub 4}. A broad absorption band of the WO{sub 4}{sup 2-} group is observed from photoluminescence and the energy transfer from WO{sub 4}{sup 2-} group to Tb{sup 3+} ions induces the f-f transition. The cross-relaxation between two adjacent Tb{sup 3+} ions weakens {sup 5}D{sub 3}-{sup 7}F{sub j} transitions and enhances the {sup 5}D{sub 4}-{sup 7}F{sub j} transitions, leading to a green long afterglow of the phosphors. The thermoluminescence curves centered around 75 Degree-Sign C reveal the trap depth for afterglow generation is about 0.74-0.77 eV. The optimum Tb{sup 3+} concentration for afterglow properties is about 1%. A deep hole trap is induced when Tb{sup 3+} concentration exceeds 1% and it suppresses the thermoluminescence and the decay properties.

  10. Gas Phase Model of Surface Reactions for N{2} Afterglows

    NASA Astrophysics Data System (ADS)

    Marković, V. Lj.; Petrović, Z. Lj.; Pejović, M. M.

    1996-07-01

    The adequacy of the homogeneous gas phase model as a representation of the surface losses of diffusing active particles in gas phase is studied. As an example the recent data obtained for the surface recombination coefficients are reanalyzed. The data were obtained by the application of the breakdown delay times which consists of the measurements of the breakdown delay times t_d as a function of the afterglow period tau. It was found that for the conditions of our experiment, the diffusion should not be neglected as the final results are significantly different when obtained by approximate gas phase representation and by exact numerical solution to the diffusion equation. While application of the gas phase effective coefficients to represent surface losses gives an error in the value of the recombination coefficient, it reproduces correctly other characteristics such as order of the process which can be obtained from simple fits to the experimental data. Dans cet article, nous étudions la validité du modèle approximatif représentant les pertes superficielles des particules actives qui diffusent de la phase gazeuse comme pertes dans la phase homogène du gaz. Les données actuelles du coefficient de recombination en surface sont utilisées par cette vérification . Les données experimentales sont obtenues en utilisant la technique qui consiste en la mesure du temps de retard du début de la décharge en fonction de la période de relaxation. Nous avons trouvé que, pour nos conditions expérimentales, la diffusion ne peut être négligée. Aussi, les résultats finals sont considérablement différents quand ils sont obtenus en utilisant le modèle approximatif par comparaison aves les résultats obtenus par la solution numérique exacte de l'équation de la diffusion. L'application des coefficients effectifs dans la phase gaseuse pour la présentation des pertes superficielles donne, pour les coefficients de la recombinaison, des valeurs qui diffèrent en

  11. Luminescence and afterglow in Sr{sub 2}SiO{sub 4}:Eu{sup 2+}, RE{sup 3+} [RE = Ce, Nd, Sm and Dy] phosphors-Role of co-dopants in search for afterglow

    SciTech Connect

    Lakshminarasimhan, N. Varadaraju, U.V.

    2008-11-03

    Luminescence of Eu{sup 2+} in Sr{sub 2}SiO{sub 4}:Eu{sup 2+}, RE{sup 3+} [RE = Ce, Nd, Sm and Dy] phosphors was studied with a view to obtain an afterglow phosphor. The synthesized phosphors were characterized by powder X-ray diffraction (XRD), diffuse reflectance, photo- and thermoluminescence spectroscopic techniques. Afterglow was observed only with Dy{sup 3+} co-doped phosphor. The observed afterglow with Dy{sup 3+} co-doping originated from the formation of suitable traps which was supported by thermoluminescence results.

  12. Determination of cosmological parameters from gamma ray burst characteristics and afterglow correlations

    NASA Astrophysics Data System (ADS)

    Zitouni, H.; Guessoum, N.; Azzam, W. J.

    2016-12-01

    We use the correlation relation between the energy emitted by the GRBs in their prompt phases and the X-ray afterglow fluxes, in an effort to constrain cosmological parameters and aiming to construct a Hubble diagram at high redshifts, i.e. beyond those found with Type Ia supernovae.

  13. CORRELATED SPECTRAL AND TEMPORAL BEHAVIOR OF LATE-TIME AFTERGLOWS OF GAMMA-RAY BURSTS

    SciTech Connect

    Dado, Shlomo; Dar, Arnon

    2012-12-20

    The cannonball (CB) model of gamma-ray bursts (GRBs) predicts that the asymptotic behavior of the spectral energy density of GRB afterglows is a power law in time and in frequency, and the difference between the temporal and spectral power-law indices, {alpha}{sub X} - {beta}{sub X}, is restricted to the values 0, 1/2, and 1. Here we report the distributions of the values {alpha}{sub X} and {beta}{sub X}, and their difference for a sample of 315 Swift GRBs. This sample includes all Swift GRBs that were detected before 2012 August 1, whose X-ray afterglow extended well beyond 1 day and the estimated error in {alpha}{sub X} - {beta}{sub X} was {<=}0.25. The values of {alpha}{sub X} were extracted from the CB-model fits to the entire light curves of their X-ray afterglow while the spectral index was extracted by the Swift team from the time-integrated X-ray afterglow of these GRBs. We found that the distribution of the difference {alpha}{sub X} - {beta}{sub X} for these 315 Swift GRBs has three narrow peaks around 0, 1/2, and 1 whose widths are consistent with being due to the measurement errors, in agreement with the CB-model prediction.

  14. Investigation of the strategies for targeting of the afterglow nanoparticles to tumor cells.

    PubMed

    Rashidi, Leila Hossein; Homayoni, Homa; Zou, Xiaoju; Liu, Li; Chen, Wei

    2016-03-01

    Afterglow nanoparticles have been widely investigated as new agents for cancer imaging and as a light source for photodynamic activation for cancer treatment. For both applications, the targeting of the afterglow nanoparticles to tumor cells is an important and challenging issue. Here we report the strategies for targeting Sr3MgSi2O8:Eu(2+),Dy(3+) afterglow nanoparticles to tumor cells by conjugating with variety of targeting molecules such as folic acid, RGD peptide, and R-11 peptide. For folic acid targeting, experimental observations were conducted on PC-3 cells (folate receptor negative), MCF-7 (folate receptor positive), and KB cells (folate receptor positive) to compare the cellular uptake and confirm targeted delivery. For the cyclic RGDfK peptide, experiments were carried out on the integrin αvβ3 positive MDA-MB-231 breast cancer cell line and the integrin αvβ3 negative MCF-7 breast cancer cell lines in order to compare the cellular uptakes. As for R11-SH peptide, cellular uptake of the afterglow nanoparticles was observed on LNCaP and PC3 prostate cancer cell lines. All the observations showed that the cellular uptakes of the nanoparticles were enhanced by conjugation to variety of targeting molecules which are specific for breast and prostate cancer cells.

  15. Investigation on the effect of exposure time on scintillator afterglow for ultra-fast tomography acquisition

    NASA Astrophysics Data System (ADS)

    Zefreh, K. Z.; Welford, F. M.; Sijbers, Jan

    2016-12-01

    Thanks to the ultra-fast endstation of the TOMCAT beamline, it is possible to do a tomographic scan with a sub-second temporal resolution which allows following dynamic processes in 4D (3D space + time). This ultra- high-rate tomography acquisition, exploiting the distinctive peculiarities of synchrotron radiation, provides nondestructive investigation of many dynamic processes which were not possible in the past. For example a continuous tensile test has been conducted recently in-situ for the first time with a frequency of 20 tomograms per second (20 Hz acquisition frequency). In the ultra-fast endstation a scintillator is used to convert X-ray to visible photons that can be detected by the camera. However, this conversion is not ideal and the scintillator response decays exponentially with afterglow. Afterglow can cause resolution degradation and artifacts (such as ring and band) especially with high rotation speed. On the other hand, to achieve a higher scan speed, thicker scintillators are more common because they result in higher emission intensities that can compensate the short exposure time in fast scans. However, the resolution deteriorates as the scintillator's thickness increases and thicker scintillators show higher afterglow. Performing many ultra-fast scans at the TOMCAT beamline with different acquisition rate, we demonstrate how the exposure time effects on the projection data and reconstructed images. Using two different thicknesses of LAG scintillator we also investigate the afterglow artifacts for different acquisition rate and exposure time.

  16. Polarization Evolution of Early Optical Afterglows of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Lan, Mi-Xiang; Wu, Xue-Feng; Dai, Zi-Gao

    2016-01-01

    The central engine and jet composition of gamma-ray bursts (GRBs) remain mysterious. Here we suggest that observations on the polarization evolution of early optical afterglows may shed light on these questions. We first study the dynamics of a reverse shock and a forward shock that are generated during the interaction of a relativistic jet and its ambient medium. The jet is likely magnetized with a globally large-scale magnetic field from the central engine. The existence of the reverse shock requires that the magnetization degree of the jet should not be high (σ ≤ 1), so that the jet is mainly composed of baryons and leptons. We then calculate the light curves and polarization evolution of early optical afterglows and find that when the polarization position angle changes by 90° during the early afterglow, the polarization degree is zero for a toroidal magnetic field but is very likely to be nonzero for an aligned magnetic field. This result would be expected to provide a probe for the central engine of GRBs because an aligned field configuration could originate from a magnetar central engine and a toroidal field configuration could be produced from a black hole via the Blandford-Znajek mechanism. Finally, for such two kinds of magnetic field configurations, we fit the observed data of the early optical afterglow of GRB 120308A equally well.

  17. BRIGHT BROADBAND AFTERGLOWS OF GRAVITATIONAL WAVE BURSTS FROM MERGERS OF BINARY NEUTRON STARS

    SciTech Connect

    Gao He; Ding Xuan; Wu Xuefeng; Zhang Bing; Dai Zigao E-mail: zhang@physics.unlv.edu

    2013-07-10

    If double neutron star mergers leave behind a massive magnetar rather than a black hole, then a bright early afterglow can follow the gravitational wave burst (GWB) even if there is no short gamma-ray burst (SGRB)-GWB association or if there is an association but the SGRB does not beam toward Earth. Besides directly dissipating the proto-magnetar wind, as suggested by Zhang, here we suggest that the magnetar wind could push the ejecta launched during the merger process and, under certain conditions, would reach a relativistic speed. Such a magnetar-powered ejecta, when interacting with the ambient medium, would develop a bright broadband afterglow due to synchrotron radiation. We study this physical scenario in detail and present the predicted X-ray, optical, and radio light curves for a range of magnetar and ejecta parameters. We show that the X-ray and optical light curves usually peak around the magnetar spin-down timescale ({approx}10{sup 3}-10{sup 5} s), reaching brightnesses readily detectable by wide-field X-ray and optical telescopes, and remain detectable for an extended period. The radio afterglow peaks later, but is much brighter than the case without a magnetar energy injection. Therefore, such bright broadband afterglows, if detected and combined with GWBs in the future, would be a probe of massive millisecond magnetars and stiff equations of state for nuclear matter.

  18. Early GRB Afterglows from Reverse Shocks in Ultra-relativistic, Long-lasting Winds

    NASA Astrophysics Data System (ADS)

    Lyutikov, Maxim; Camilo Jaramillo, Juan

    2017-02-01

    We develop a model of early Gamma-Ray Burst (GRB) afterglows with dominant X-ray contribution from the reverse shock (RS) propagating in highly relativistic (Lorentz factor γw ∼ 106) magnetized wind of a long-lasting central engine. The model reproduces, in a fairly natural way, the overall trends and yet allows for variations in the temporal and spectral evolution of early optical and X-ray afterglows. The high energy and the optical synchrotron emission from the RS particles occurs in the fast cooling regime; the resulting synchrotron power Ls is a large fraction of the wind luminosity, {L}s≈ {L}w/\\sqrt{1+{σ }w} (Lw and σw are wind power and magnetization). Thus, plateaus—parts of afterglow light curves that show slowly decreasing spectral power—are a natural consequence of the RS emission. Contribution from the forward shock (FS) is negligible in the X-rays, but in the optical both FS and RS contribute similarly: FS optical emission is in the slow cooling regime, producing smooth components, while RS optical emission is in the fast cooling regime, and thus can both produce optical plateaus and account for fast optical variability correlated with the X-rays, e.g., due to changes in the wind properties. We discuss how the RS emission in the X-rays and combined FS and RS emission in the optical can explain many puzzling properties of early GRB afterglows.

  19. POLARIZATION EVOLUTION OF EARLY OPTICAL AFTERGLOWS OF GAMMA-RAY BURSTS

    SciTech Connect

    Lan, Mi-Xiang; Dai, Zi-Gao; Wu, Xue-Feng

    2016-01-10

    The central engine and jet composition of gamma-ray bursts (GRBs) remain mysterious. Here we suggest that observations on the polarization evolution of early optical afterglows may shed light on these questions. We first study the dynamics of a reverse shock and a forward shock that are generated during the interaction of a relativistic jet and its ambient medium. The jet is likely magnetized with a globally large-scale magnetic field from the central engine. The existence of the reverse shock requires that the magnetization degree of the jet should not be high (σ ≤ 1), so that the jet is mainly composed of baryons and leptons. We then calculate the light curves and polarization evolution of early optical afterglows and find that when the polarization position angle changes by 90° during the early afterglow, the polarization degree is zero for a toroidal magnetic field but is very likely to be nonzero for an aligned magnetic field. This result would be expected to provide a probe for the central engine of GRBs because an aligned field configuration could originate from a magnetar central engine and a toroidal field configuration could be produced from a black hole via the Blandford–Znajek mechanism. Finally, for such two kinds of magnetic field configurations, we fit the observed data of the early optical afterglow of GRB 120308A equally well.

  20. Implications of the Early X-Ray Afterglow Light Curves of Swift GRBs

    SciTech Connect

    Granot, Jonathan; Konigl, Arieh; Piran, Tsvi; /Hebrew U.

    2006-01-17

    According to current models, gamma-ray bursts (GRBs) are produced when the energy carried by a relativistic outflow is dissipated and converted into radiation. The efficiency of this process, {epsilon}{sub {gamma}}, is one of the critical factors in any GRB model. The X-ray afterglow light curves of Swift GRBs show an early stage of flattish decay. This has been interpreted as reflecting energy injection. When combined with previous estimates, which have concluded that the kinetic energy of the late ({approx}> 10 hr) afterglow is comparable to the energy emitted in {gamma}-rays, this interpretation implies very high values of {epsilon}{sub {gamma}}, corresponding to {approx}> 90% of the initial energy being converted into {gamma}-rays. Such a high efficiency is hard to reconcile with most models, including in particular the popular internal-shocks model. We re-analyze the derivation of the kinetic energy from the afterglow X-ray flux and re-examine the resulting estimates of the efficiency. We confirm that, if the flattish decay arises from energy injection and the pre-Swift broad-band estimates of the kinetic energy are correct, then {epsilon}{sub {gamma}} {approx}> 0.9. We discuss various issues related to this result, including an alternative interpretation of the light curve in terms of a two-component outflow model, which we apply to the X-ray observations of GRB 050315. We point out, however, that another interpretation of the flattish decay--a variable X-ray afterglow efficiency (e.g., due to a time dependence of afterglow shock microphysical parameters)--is possible. We also show that direct estimates of the kinetic energy from the late X-ray afterglow flux are sensitive to the assumed values of the shock microphysical parameters and suggest that broad-band afterglow fits might have underestimated the kinetic energy (e.g., by overestimating the fraction of electrons that are accelerated to relativistic energies). Either one of these possibilities implies a

  1. The Late-time Afterglow of the Extremely Energetic Short Burst GRB 090510 Revisited

    NASA Technical Reports Server (NTRS)

    Guelbenzu, A. Nicuesa; Klose, S.; Kruehler, T.; Greiner, J.; Rossi, A.; Kann, D. A.; Olivares, F.; Rau, A.; Afonso, P. M. J.; Elliott, J.; Filgas, R.; Yoldas, A. Kuepcue; McBreen, S.; Nardini, M.; Schady, P.; Schmidl, S.; Sudilovsky, V.; Updike, A. C.; Yoldas, A.

    2012-01-01

    Context. The Swift discovery of the short burst GRB 090510 has raised considerable attention mainly because of two reasons: first, it had a bright optical afterglow, and second it is among the most energetic events detected so far within the entire GRB population (long plus short). The afterglow of GRB 090510 was observed with Swift/UVOT and Swift/XRT and evidence of a jet break around 1.5 ks after the burst has been reported in the literature, implying that after this break the optical and X-ray light curve should fade with the same decay slope. Aims. As noted by several authors, the post-break decay slope seen in the UVOT data is much shallower than the steep decay in the X-ray band, pointing to a (theoretically hard to understand) excess of optical flux at late times. We assess here the validity of this peculiar behavior. Methods. We reduced and analyzed new afterglow light-curve data obtained with the multichannel imager GROND. These additional g'r'i'z' data were then combined with the UVOT and XRT data to study the behavior of the afterglow at late times more stringently. Results. Based on the densely sampled data set obtained with GROND, we find that the optical afterglow of GRB 090510 did indeed enter a steep decay phase starting around 22 ks after the burst. During this time the GROND optical light curve is achromatic, and its slope is identical to the slope of the X-ray data. In combination with the UVOT data this implies that a second break must have occurred in the optical light curve around 22 ks post burst, which, however, has no obvious counterpart in the X-ray band, contradicting the interpretation that this could be another jet break. Conclusions. The GROND data provide the missing piece of evidence that the optical afterglow of GRB 090510 did follow a post-jet break evolution at late times. The break seen in the optical light curve around 22 ks in combination with its missing counterpart in the X-ray band could be due to the passage of the

  2. Dust extinctions for an unbiased sample of gamma-ray burst afterglows

    NASA Astrophysics Data System (ADS)

    Covino, S.; Melandri, A.; Salvaterra, R.; Campana, S.; Vergani, S. D.; Bernardini, M. G.; D'Avanzo, P.; D'Elia, V.; Fugazza, D.; Ghirlanda, G.; Ghisellini, G.; Gomboc, A.; Jin, Z. P.; Krühler, T.; Malesani, D.; Nava, L.; Sbarufatti, B.; Tagliaferri, G.

    2013-06-01

    In this paper, we compute rest-frame extinctions for the afterglows of a sample of Swift gamma-ray bursts (GRBs) complete in redshift. The selection criteria of the sample are based on observational high-energy parameters of the prompt emission and therefore our sample should not be biased against dusty sight-lines. It is therefore expected that our inferences hold for the general population of GRBs. Our main result is that the optical/near-infrared extinction of GRB afterglows in our sample does not follow a single distribution. 87 per cent of the events are absorbed by less than 2 mag, and 50 per cent suffer from less than 0.3-0.4 mag extinction. The remaining 13 per cent of the afterglows are highly absorbed. The true percentage of GRB afterglows showing high absorption could be even higher since a fair fraction of the events without reliable redshift measurement are probably part of this class. These events may be due to highly dusty molecular clouds/star-forming regions associated with the GRB progenitor or along the afterglow line of sight, and/or due to massive dusty host galaxies. No clear evolution in the dust extinction properties is evident within the redshift range of our sample, although the largest extinctions are at z ˜ 1.5-2, close to the expected peak of the star formation rate. Those events classified as dark are characterized, on average, by a higher extinction than typical events in the sample. A correlation between optical/near-infrared extinction and hydrogen-equivalent column density based on X-ray studies is shown, although the observed NH appears to be well in excess compared to those observed in the Local Group. Dust extinction does not seem to correlate with GRB energetics or luminosity.

  3. Discovery and Observations of the Optical Afterglow of GRB 071010B

    NASA Astrophysics Data System (ADS)

    Oksanen, A.; Templeton, M.; Henden, A. A.; Kann, D. A.

    2008-06-01

    On 2007 October 10 at 20:45:48 UT, the Swift satellite detected the bright, long-soft gamma-ray burst GRB 071010B in the constellation Ursa Major. Coordinates were automatically distributed via the Gamma-ray Burst Coordinate Network (GCN), and observations were begun by A. Oksanen at the Hankasalmi Observatory in Hankasalmi, Finland, within fifteen minutes of the burst. A previously uncatalogued optical source was detected at R.A. 10h 02m 09.26s, Dec. +45° 43' 50.3'' (J2000) at an unfiltered (R-band calibrated) magnitude of approximately 17.5. Imaging over the following six hours showed that the source faded, indicating that it was likely the optical afterglow of GRB 071010B. The discovery was published via the GCN Circulars, and the coordinates were subsequently used by other major telescope facilities to conduct follow-up photometry and spectroscopy. The discovery of the optical afterglow by A. Oksanen is the first discovery of a GRB afterglow by an amateur astronomer since the discovery of GRB 030725 by L. A. G. Monard in 2003 (Monard 2003). The early detection of this afterglow and subsequent dissemination of coordinates via the GCN has proved very valuable from a scientific standpoint. These data are the earliest available photometry for this burst, enabling the study of the early stages of the GRB optical light. They were also the first localization, and these coordinates were subsequently used by other major optical facilities for their follow-up observations. This burst clearly shows that individual observers still have a role to play in GRB observations even in the era of automated, robotic telescopes, and that the amateur community is an important partner of the professional community in the observation of GRB afterglows.

  4. The puzzling afterglow of GRB 050721: a rebrightening seen in the optical but not in the X-ray

    SciTech Connect

    Antonelli, L. A.; Romano, P.; Testa, V.; D'Elia, V.; Guetta, D.; Torii, K.; Malesani, D.

    2007-08-21

    We present here the analysis of the early and late multiwavelength afterglow emission, as observed by Swift a small robotic telescope, and the VLT. We compare early observations with late afterglow observations obtained with Swift and the VLT and we observe an intense rebrightening in the optical band at about one day after the burst which is not present in the X-ray band. The lack of detection in X-ray of such a strong rebrightening at lower energies may be described with a variable external density profile. In such a scenario, the combined X-ray and optical observations allow us to derive that the matter density located at {approx} 1017 cm from the burst is about a factor of 10 higher than in the inner region. This is the first time in which a rebrightening has been observed in the optical afterglow of a GRB that is clearly absent in the X-ray afterglow.

  5. THE PROPERTIES OF THE 2175 A EXTINCTION FEATURE DISCOVERED IN GRB AFTERGLOWS

    SciTech Connect

    Zafar, Tayyaba; Watson, Darach; Eliasdottir, Ardis; Fynbo, Johan P. U.; Kruehler, Thomas; Leloudas, Giorgos; Schady, Patricia; Greiner, Jochen; Jakobsson, Pall; Thoene, Christina C.; Perley, Daniel A.; Morgan, Adam N.; Bloom, Joshua E-mail: darach@dark-cosmology.dk

    2012-07-01

    The unequivocal, spectroscopic detection of the 2175 A bump in extinction curves outside the Local Group is rare. To date, the properties of the bump have been examined in only two gamma-ray burst (GRB) afterglows (GRB 070802 and GRB 080607). In this work, we analyze in detail the detections of the 2175 Angstrom-Sign extinction bump in the optical spectra of two further GRB afterglows: GRB 080605 and 080805. We gather all available optical/near-infrared photometric, spectroscopic, and X-ray data to construct multi-epoch spectral energy distributions (SEDs) for both GRB afterglows. We fit the SEDs with the Fitzpatrick and Massa model with a single or broken power law. We also fit a sample of 38 GRB afterglows, known to prefer a Small Magellanic Cloud (SMC)-type extinction curve, with the same model. We find that the SEDs of GRB 080605 and GRB 080805 at two epochs are fit well with a single power law with a derived extinction of A{sub V} = 0.52{sup +0.13}{sub -0.16} and 0.50{sup +0.13}{sub -0.10}, and 2.1{sup +0.7}{sub -0.6} and 1.5 {+-} 0.2, respectively. While the slope of the extinction curve of GRB 080805 is not well constrained, the extinction curve of GRB 080605 has an unusual very steep far-UV rise together with the 2175 A bump. Such an extinction curve has previously been found in only a small handful of sightlines in the Milky Way. One possible explanation of such an extinction curve may be dust arising from two different regions with two separate grain populations, however we cannot distinguish the origin of the curve. We finally compare the four 2175 A bump sightlines to the larger GRB afterglow sample and to Local Group sightlines. We find that while the width and central positions of the bumps are consistent with what is observed in the Local Group, the relative strength of the detected bump (A{sub bump}) for GRB afterglows is weaker for a given A{sub V} than for almost any Local Group sightline. Such dilution of the bump strength may offer tentative

  6. Radio Observations Of GRB 100418a: Test Of An Energy Injection Model Explaining Long-Lasting GRB Afterglows

    NASA Astrophysics Data System (ADS)

    Moin, Aquib; Chandra, P.; Miller-Jones, J.; Tingay, S.; Taylor, G. B.; Frail, D. A.; Wang, Z.; Reynolds, C.; Phillips, C.

    2014-01-01

    I will highlight the results of our radio observational campaign on GRB 100418a, for which the Australia Telescope Compact Array (ATCA), Very Large Array (VLA) and the Very Long Baseline Array (VLBA) were used. GRB 100418a was a peculiar GRB with unusual X-ray and optical afterglow profiles featuring a plateau phase with a very shallow rise. This observed plateau phase was believed to be due to a continued energy injection mechanism, which powered the forward shock, giving rise to an unusual and long-lasting afterglow. The radio afterglow of GRB 100418a was detectable several weeks after the prompt emission. We conducted long-term monitoring observations of the afterglow and attempted to test the energy injection model advocating that the continuous energy injection is due to shells of material moving at a wide range of Lorentz factors. We obtained an upper limit of γ < 7 for the expansion rate of the GRB 100418a radio afterglow, indicating that the range-of-Lorentz factor model could only be applicable for relatively slow moving ejecta. A preferred explanation could be that continued activity of the central engine may have powered the long-lasting afterglow.

  7. Radio observations of GRB 100418a: Test of an energy injection model explaining long-lasting GRB afterglows

    SciTech Connect

    Moin, A.; Wang, Z.; Chandra, P.; Miller-Jones, J. C. A.; Tingay, S. J.; Reynolds, C.; Taylor, G. B.; Frail, D. A.; Phillips, C. J.

    2013-12-20

    We present the results of our radio observational campaign of gamma-ray burst (GRB) 100418a, for which we used the Australia Telescope Compact Array, the Very Large Array, and the Very Long Baseline Array. GRB 100418a was a peculiar GRB with unusual X-ray and optical afterglow profiles featuring a plateau phase with a very shallow rise. This observed plateau phase was believed to be due to a continued energy injection mechanism that powered the forward shock, giving rise to an unusual and long-lasting afterglow. The radio afterglow of GRB 100418a was detectable several weeks after the prompt emission. We conducted long-term monitoring observations of the afterglow and attempted to test the energy injection model advocating that the continuous energy injection is due to shells of material moving at a wide range of Lorentz factors. We obtained an upper limit of γ < 7 for the expansion rate of the GRB 100418a radio afterglow, indicating that the range-of-Lorentz factor model could only be applicable for relatively slow-moving ejecta. A preferred explanation could be that continued activity of the central engine may have powered the long-lasting afterglow.

  8. Evidence for an Early High-Energy Afterglow Observed with BATSE from GRB 980923

    NASA Technical Reports Server (NTRS)

    Giblin, T. W.; vanParadijs, J.; Kouveliotou, C.; Connaughton, V.; Wijers, R. A. M. J.; Briggs, M. S.; Preece, R. D.; Fishman, G. J.

    1999-01-01

    In this Letter, we present the first evidence in the BATSE data for a prompt high-energy (25-300 keV) afterglow component from a gamma-ray burst, GRB 980923. The event consists of rapid variability lasting approximately 40 s followed by a smooth power-law emission tail lasting approximately 400 s. An abrupt change in spectral shape is found when the tail becomes noticeable. Our analysis reveals that the spectral evolution in the tail of the burst mimics that of a cooling synchrotron spectrum, similar to the spectral evolution of the low-energy afterglows for gamma-ray bursts. This evidence for a separate emission component is consistent with the internal-external shock scenario in the relativistic fireball picture. In particular, it illustrates that the external shocks can be generated during the gamma-ray emission phase, as in the case of GRB 990123.

  9. X-RAY AFTERGLOW OF SWIFT J1644+57: A COMPTON ECHO?

    SciTech Connect

    Cheng, K. S.; Chernyshov, D. O.; Dogiel, V. A.; Kong, Albert K. H.; Ko, C. M.

    2016-01-01

    Swift, Chandra, and XMM have found a weak but nearly constant X-ray component from Swift J1644+57 that appeared at ∼500 days and was visible at least until ∼1400 days after the stellar capture, which cannot be explained by standard tidal disruption theories. We suggest that this X-ray afterglow component may result from the Thomson scattering between the primary X-rays and its surrounding plasma, i.e., a Compton echo effect. Similar phenomena have also been observed from molecular clouds in our Galactic Center, which were caused by the past activity of Srg A*. If this interpretation of Swift J1644+57 afterglow is correct, this is the first Compton Echo effect observed in the cosmological distances.

  10. Optical-infrared flares and radio afterglows by Jovian planets inspiraling into their host stars

    NASA Astrophysics Data System (ADS)

    Yamazaki, Ryo; Hayasaki, Kimitake; Loeb, Abraham

    2017-04-01

    When a planet inspirals into its host star, it releases gravitational energy, which is converted into an expanding bubble of hot plasma. We study the radiation from the bubble and show that it includes prompt optical-infrared emission and a subsequent radio afterglow. The prompt emission from M31 and the Large Magellanic Cloud is detectable by optical-near-infrared transient surveys with a large field of view. The subsequent radio afterglows are detectable for 103-104 yr. The event rate depends on uncertain parameters in the formation and dynamics of giant planets. Future observations of the rate will constrain related theoretical models. If the event rate is high ( ≳ a few events per year), the circumstellar disc must typically be massive, as suggested by recent numerical simulations.

  11. The effectiveness of strong afterglow phosphor powder in the detection of fingermarks.

    PubMed

    Liu, Li; Zhang, Zhongliang; Zhang, Limei; Zhai, Yuchun

    2009-01-10

    There are numerous types of fluorescent fingermark powders or reagents used with the visualization of latent fingermarks deposited on multicolored substrate surfaces that can present a contrast problem if developed with regular fingermark powders. The developed fingermarks can show bright fluorescence upon exposure to laser, ultraviolet light and other light sources. These kinds of methods share a common concern, where surfaces and other substrates may fluoresce also. To overcome this concern, we have developed a phosphor powder which offers a strong afterglow effect which aid in the establishment of better fingermark detection. With the advent of a phosphor powder no special devices are required and the results obtained from fresh or a few days aged latent fingermarks left on: non-porous; semi-porous and also on some porous surfaces have been good. The strong afterglow effect offered by phosphor powder is also applicable for cyanoacrylate fumed fingermarks. Lift off and photography procedures of the developed fingermarks are incorporated in this paper.

  12. A Search for Early High-Energy Afterglows in BATSE Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Giblin, Timothy W.

    2003-01-01

    The scope of this project was to perform a detailed search for the early high-energy afterglow component of gamma-ray bursts (GRBs) in the BATSE GRB data archive. GRBs are believed to be the product of shock waves generated in a relativistic outflow from the demise of extremely massive stars and/or binary neutron star mergers. The outflow undeniably encounters the ambient medium of the progenitor object and another shock wave is set up. A forward shock propagates into the medium and a reverse shock propagates through the ejecta. This "external" shock dissipates the kinetic energy of the ejecta in the form of radiation via synchrotron losses and slows the outflow eventually to a non-relativistic state. Radiation from the forward external shock is therefore expected to be long-lived, lasting days, weeks, and even months. This radiation is referred to as the 'afterglow'.

  13. Pinus Pinaster surface treatment realized in spatial and temporal afterglow DBD conditions

    NASA Astrophysics Data System (ADS)

    Lecoq, E.; Clément, F.; Panousis, E.; Loiseau, J.-F.; Held, B.; Castetbon, A.; Guimon, C.

    2008-04-01

    This experimental work deals with the exposition of Pinus Pinaster wood samples to a DBD afterglow. Electrical parameters like duty cycle and injected energy in the gas are being varied and the modifications induced by the afterglow on the wood are analysed by several macroscopic and microscopic ways like wettability, XPS analyses and also soaking tests of treated wood in a commercial fungicide solution. Soaking tests show that plasma treatment could enhance the absorption of fungicide into the wood. The wettability results point out that the plasma treatment can inflict on the wood different surface properties, making it hydrophilic or hydrophobic, when varying electrical parameters. XPS analyses reveal several chemical modifications like an increase of the O/C ratio and the presence of carboxyl groups on the surface after plasma treatments.

  14. Constraining chameleon field theories using the GammeV afterglow experiments

    SciTech Connect

    Upadhye, A.; Steffen, J.H.; Weltman, A.; /Cambridge U., DAMTP /Cape Town U.

    2009-11-01

    The GammeV experiment has constrained the couplings of chameleon scalar fields to matter and photons. Here we present a detailed calculation of the chameleon afterglow rate underlying these constraints. The dependence of GammeV constraints on various assumptions in the calculation is studied. We discuss GammeV-CHASE, a second-generation GammeV experiment, which will improve upon GammeV in several major ways. Using our calculation of the chameleon afterglow rate, we forecast model-independent constraints achievable by GammeV-CHASE. We then apply these constraints to a variety of chameleon models, including quartic chameleons and chameleon dark energy models. The new experiment will be able to probe a large region of parameter space that is beyond the reach of current tests, such as fifth force searches, constraints on the dimming of distant astrophysical objects, and bounds on the variation of the fine structure constant.

  15. Afterglow chemistry of atmospheric-pressure helium-oxygen plasmas with humid air impurity

    NASA Astrophysics Data System (ADS)

    Murakami, Tomoyuki; Niemi, Kari; Gans, Timo; O'Connell, Deborah; Graham, William G.

    2014-04-01

    The formation of reactive species in the afterglow of a radio-frequency-driven atmospheric-pressure plasma in a fixed helium-oxygen feed gas mixture (He+0.5%O2) with humid air impurity (a few hundred ppm) is investigated by means of an extensive global plasma chemical kinetics model. As an original objective, we explore the effects of humid air impurity on the biologically relevant reactive species in an oxygen-dependent system. After a few milliseconds in the afterglow environment, the densities of atomic oxygen (O) decreases from 1015 to 1013 cm-3 and singlet delta molecular oxygen (O2(1D)) of the order of 1015 cm-3 decreases by a factor of two, while the ozone (O3) density increases from 1014 to 1015 cm-3. Electrons and oxygen ionic species, initially of the order of 1011 cm-3, recombine much faster on the time scale of some microseconds. The formation of atomic hydrogen (H), hydroxyl radical (OH), hydroperoxyl (HO2), hydrogen peroxide (H2O2), nitric oxide (NO) and nitric acid (HNO3) resulting from the humid air impurity as well as the influence on the afterglow chemistry is clarified with particular emphasis on the formation of dominant reactive oxygen species (ROS). The model suggests that the reactive species predominantly formed in the afterglow are major ROS O2(1D) and O3 (of the order of 1015 cm-3) and rather minor hydrogen- and nitrogen-based reactive species OH, H2O2, HNO3 and NO2/NO3, of which densities are comparable to the O-atom density (of the order of 1013 cm-3). Furthermore, the model quantitatively reproduces the experimental results of independent O and O3 density measurements.

  16. Phenomenology of reverse-shock emission in the optical afterglows of gamma-ray bursts

    SciTech Connect

    Japelj, J.; Kopač, D.; Gomboc, A.; Kobayashi, S.; Harrison, R.; Virgili, F. J.; Mundell, C. G.; Guidorzi, C.; Melandri, A. E-mail: andreja.gomboc@fmf.uni-lj.si

    2014-04-20

    We use a parent sample of 118 gamma-ray burst (GRB) afterglows, with known redshift and host galaxy extinction, to separate afterglows with and without signatures of dominant reverse-shock (RS) emission and to determine which physical conditions lead to a prominent reverse-shock emission. We identify 10 GRBs with reverse-shock signatures: 990123, 021004, 021211, 060908, 061126, 080319B, 081007, 090102, 090424, and 130427A. By modeling their optical afterglows with reverse- and forward-shock analytic light curves and using Monte Carlo simulations, we estimate the parameter space of the physical quantities describing the ejecta and circumburst medium. We find that physical properties cover a wide parameter space and do not seem to cluster around any preferential values. Comparing the rest-frame optical, X-ray, and high-energy properties of the larger sample of non-RS-dominated GRBs, we show that the early-time (<1 ks) optical spectral luminosity, X-ray afterglow luminosity, and γ-ray energy output of our reverse-shock dominated sample do not differ significantly from the general population at early times. However, the GRBs with dominant reverse-shock emission have fainter than average optical forward-shock emission at late times (>10 ks). We find that GRBs with an identifiable reverse-shock component show a high magnetization parameter R {sub B} = ε{sub B,r}/ε{sub B,f} ∼ 2-10{sup 4}. Our results are in agreement with the mildly magnetized baryonic jet model of GRBs.

  17. Detection of the Optical Afterglow of GRB 000630: Implications for Dark Bursts

    DTIC Science & Technology

    2001-01-01

    erated on the island of La Palma by the Centro Galileo Galilei 1. Introduction The discoveries of the first X-ray afterglow (Costa et al. 1997) and...Association, U. S. Naval Observatory, Flagstaff Station, PO Box 1149, Flagstaff, AZ 86002-1149, USA 9 Telescopio Nazionale Galileo , Apartado Postal 565, 38700...images with the 3.5-m Telescopio Nazionale Galileo (TNG). The journal of observations is reported in Table 1. 3. Results 3.1. Astrometry By measuring

  18. Evolution of dust content in galaxies probed by gamma-ray burst afterglows

    NASA Astrophysics Data System (ADS)

    Kuo, Tzu-Ming; Hirashita, Hiroyuki; Zafar, Tayyaba

    2013-12-01

    Because of their brightness, gamma-ray burst (GRB) afterglows are viable targets for investigating the dust content in their host galaxies. Simple intrinsic spectral shapes of GRB afterglows allow us to derive the dust extinction. Recently, the extinction data of GRB afterglows are compiled up to redshift z = 6.3, in combination with hydrogen column densities and metallicities. This data set enables us to investigate the relation between dust-to-gas ratio and metallicity out to high redshift for a wide metallicity range. By applying our evolution models of dust content in galaxies, we find that the dust-to-gas ratios derived from GRB afterglow extinction data are excessively high such that they can be explained with a fraction of gas-phase metals condensed into dust (fin) ˜ 1, while theoretical calculations on dust formation in the wind of asymptotic giant branch stars and in the ejecta of Type II supernovae suggest a much more moderate condensation efficiency (fin ˜ 0.1). Efficient dust growth in dense clouds has difficulty in explaining the excessive dust-to-gas ratio at metallicities Z/Z⊙ < ɛ, where ɛ is the star formation efficiency of the dense clouds. However, if ɛ is as small as 0.01, the dust-to-gas ratio at Z ˜ 10-2 Z⊙ can be explained with nH ≳ 106 cm-3. Therefore, a dense environment hosting dust growth is required to explain the large fraction of metals condensed into dust, but such clouds should have low star formation efficiencies to avoid rapid metal enrichment by stars.

  19. The Dynamics and Afterglow Radiation of Gamma-Ray Bursts. I. Constant Density Medium

    NASA Astrophysics Data System (ADS)

    Zhang, Weiqun; MacFadyen, Andrew

    2009-06-01

    Direct multidimensional numerical simulation is the most reliable approach for calculating the fluid dynamics and observational signatures of relativistic jets in gamma-ray bursts (GRBs). We present a two-dimensional relativistic hydrodynamic simulation of a GRB outflow during the afterglow phase, which uses the fifth-order weighted essentially nonoscillatory scheme and adaptive mesh refinement. Initially, the jet has a Lorentz factor of 20. We have followed its evolution up to 150 years. Using the hydrodynamic data, we calculate synchrotron radiation based upon standard afterglow models and compare our results with previous analytic work. We find that the sideways expansion of a relativistic GRB jet is a very slow process and previous analytic works have overestimated its rate. In our computed light curves, a very sharp jet break is seen and the postbreak light curves are steeper than analytic predictions. We find that the jet break in GRB afterglow light curves is mainly caused by the missing flux when the edge of the jet is observed. The outflow becomes nonrelativistic at the end of the Blandford-McKee phase. But it is still highly nonspherical, and it takes a rather long time for it to become a spherical Sedov-von Neumann-Taylor blast wave. We find that the late-time afterglows become increasingly flatter over time. But we disagree with the common notion that there is a sudden flattening in light curves due to the transition into the Sedov-von Neumann-Taylor solution. We have also found that there is a bump in light curves at very late times (~1000 days) due to radiation from the counter jet. We speculate that such a counter jet bump might have already been observed in GRB 980703.

  20. Shock-wave-induced enhancement of optical emission in nitrogen afterglow plasma

    SciTech Connect

    Siefert, N.; Ganguly, B.N.; Bletzinger, P.

    2005-12-15

    This paper reports measurements of optical emission enhancement at the shock front of Mach 1.5 to Mach 3.5 shockwaves propagating in the afterglow of a 0.75 Torr nitrogen glow discharge. Electrically-generated shocks pass through the afterglow and create noticeable enhancements of the B {sup 3}{pi}{sub g}-A {sup 3}{sigma}{sub u}{sup +} and C {sup 3}{pi}{sub u}-B {sup 3}{pi}{sub g} transitions of nitrogen. Under our discharge conditions, the electron Debye length was approximately the same magnitude as the shock thickness; this allows the possibility of a space-charge region extending beyond the neutral shockwave discontinuity. Previous researchers have measured enhancement in the B {sup 3}{pi}{sub g}-A {sup 3}{sigma}{sub u}{sup +} optical emission at the shock front, but only in the active discharge. Fibers connected to photomultipler tubes measure the optical emission from the discharge. Laser deflection measures the shock velocity. The data reveals that the emission enhancement increases with Mach number, and also indicates that the emission enhancement decreases exponentially with time in the afterglow. Since the discharge voltage has already been shut off, the energy needed to create the emission enhancement cannot come from the power supply. We conclude that under our discharge conditions there is an increase in the already non-equilibrium energy of the electrons at the shock front via a shockwave-induced strong double layer.

  1. Novel methods for measuring afterglow in developmental scintillators for X-ray and neutron detection

    NASA Astrophysics Data System (ADS)

    Bartle, C. M.; Edgar, A.; Dixie, L.; Varoy, C.; Piltz, R.; Buchanan, S.; Rutherford, K.

    2011-09-01

    In this paper we discuss two novel methods of measuring afterglow in scintillators. One method is designed for X-ray detection and the other for neutron detection applications. In the first method a commercial fan-beam scanner of basic design similar to those seen at airports is used to deliver a typically 12 ms long X-ray pulse to a scintillator by passing the test equipment through the scanner on the conveyor belt. In the second method the thermal neutron beam from a research reactor is incident on the scintillator. The beam is cut-off in about 1 ms using a 10B impregnated aluminum pneumatic shutter, and the afterglow is recorded on a dual range storage oscilloscope to capture both the steady state intensity and the weak decay. We describe these measurement methods and the results obtained for a range of developmental ceramic and glass scintillators, as well as some standard scintillators such as NaI(Tl), LiI(Eu) and the plastic scintillator NE102A. Preliminary modeling of the afterglow is presented.

  2. REM/ROSS: a powerful tool for monitoring the prompt afterglow of γ-ray bursts

    NASA Astrophysics Data System (ADS)

    Tagliaferri, G.; Zerbi, F. M.; Chincarini, G.; Ghisellini, G.; Rodonò, M.; Palazzi, E.; Antonelli, L. A.; Conconi, P.; Covino, S.; Cutispoto, G.; Molinari, E.; Nicastro, L.; Tosti, G.; REM/ROSS Team

    2004-01-01

    Observations of the prompt afterglow of γ-ray burst events are unanimously considered of paramount importance for GRB science and cosmology. Such observations at NIR wavelengths are even more promising allowing the monitoring of high- z Ly-α absorbed bursts as well as events occurring in dusty star-forming regions. In these pages we present rapid eye mount (REM), a fully robotized fast slewing telescope equipped with a high throughput NIR (Z, J, H, K) camera dedicated to detecting the prompt IR afterglow. REM can discover objects at extremely high redshift and trigger large telescopes to observe them. The REM telescope will simultaneously feed REM optical slitless spectrograph (ROSS) via a dichroic. ROSS will intensively monitor the prompt optical continuum of GRB afterglows. The synergy between the REM-IR camera and the ROSS spectrograph makes REM a powerful observing tool for any kind of fast transient phenomena. Beside its ambitious scientific goals, REM is also technically challenging since it represent the first attempt to locate a NIR camera on a small telescope providing, with ROSS, unprecedented simultaneous wavelength coverage on a telescope of this size.

  3. GRB afterglows: Dust extinction properties from the low to high redshift universe

    NASA Astrophysics Data System (ADS)

    Zafar, Tayyaba

    2016-11-01

    Long-duration Gamma-ray bursts (GRBs) are excellent probes to study dust extinction due to their occurrence in star-forming regions and having simple synchrotron emission spectra. Inclusion of spectroscopic data to the GRB X-ray to the infrared spectral energy distribution (SED) could better define the continuum and confirm extinction feature. A preliminary SED analysis of GRB afterglows targeted with the VLT/X-Shooter spectrograph finds that all the 60% of extinguished bursts fit-well with featureless extinction curves. The longer wavelength coverage from ultraviolet to the near-infrared of X-Shooter helps to derive individual extinction curves and determine the total-to-selective extinction, RV precisely, suggesting extinction curves steeper (with a mean of RV = 2.66 ± 0.10) than the Small Magellanic Cloud. Moreover, addition of more data to the study of dust-to-metals ratios in GRB afterglows, quasar absorbers, and multiply lensed galaxies still shows the dust-to-metals ratios close to the Galactic value (with a mean value of log - 21.2cm-2mag-1), hinting short time delay between metals and dust formation. Such studies demonstrate the strength of using GRB afterglows to study dust origin and its properties the from low to high redshift Universe.

  4. Afterglow Population Studies from Swift Follow-Up Observations of Fermi LAT GRBs

    NASA Technical Reports Server (NTRS)

    Racusin, Judith L.; Oates, S. R.; McEnery, J.; Vasileiou, V.; Troja, E.; Gehrels, N.

    2010-01-01

    The small population of Fermi LAT detected GRBs discovered over the last year has been providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last 5 years, it has been Swift that has provided the robust data set of UV/optical and X-ray afterglow observations that opened many windows into other components of GRB emission structure. We explore the new ability to utilize both of these observatories to study the same GRBs over 10 orders of magnitude in energy, although not always concurrently. Almost all LAT GRBs that have been followed-up by Swift within 1-day have been clearly detected and carefully observed. We will present the context of the lower-energy afterglows of this special subset of GRBs that has > 100 MeV emission compared to the hundreds in the Swift database that may or may not have been observed by LAT, and theorize upon the relationship between these properties and the origin of the high energy gamma-ray emission.

  5. Estimates for Lorentz factors of gamma-ray bursts from early optical afterglow observations

    SciTech Connect

    Hascoët, Romain; Beloborodov, Andrei M.; Daigne, Frédéric; Mochkovitch, Robert

    2014-02-10

    The peak time of optical afterglow may be used as a proxy to constrain the Lorentz factor Γ of the gamma-ray burst (GRB) ejecta. We revisit this method by including bursts with optical observations that started when the afterglow flux was already decaying; these bursts can provide useful lower limits on Γ. Combining all analyzed bursts in our sample, we find that the previously reported correlation between Γ and the burst luminosity L {sub γ} does not hold. However, the data clearly show a lower bound Γ{sub min} that increases with L {sub γ}. We suggest an explanation for this feature: explosions with large jet luminosities and Γ < Γ{sub min} suffer strong adiabatic cooling before their radiation is released at the photosphere; they produce weak bursts, barely detectable with present instruments. To test this explanation, we examine the effect of adiabatic cooling on the GRB location in the L {sub γ} – Γ plane using a Monte Carlo simulation of the GRB population. Our results predict detectable on-axis 'orphan' afterglows. We also derive upper limits on the density of the ambient medium that decelerates the explosion ejecta. We find that the density in many cases is smaller than expected for stellar winds from normal Wolf-Rayet progenitors. The burst progenitors may be peculiar massive stars with weaker winds, or there might exist a mechanism that reduces the stellar wind a few years before the explosion.

  6. Optical flashes from internal pairs formed in gamma-ray burst afterglows

    DOE PAGES

    Panaitescu, A.

    2015-06-09

    We develop a numerical formalism for calculating the distribution with energy of the (internal) pairs formed in a relativistic source from unscattered MeV–TeV photons. For gamma-ray burst (GRB) afterglows, this formalism is more suitable if the relativistic reverse shock that energizes the ejecta is the source of the GeV photons. The number of pairs formed is set by the source GeV output (calculated from the Fermi-LAT fluence), the unknown source Lorentz factor, and the unmeasured peak energy of the LAT spectral component. We show synchrotron and inverse-Compton light curves expected from pairs formed in the shocked medium and identify some criteria for testing a pair origin of GRB optical counterparts. Pairs formed in bright LAT afterglows with a Lorentz factor in the few hundreds may produce bright optical counterparts (more » $$R\\lt 10$$) lasting for up to one hundred seconds. As a result, the number of internal pairs formed from unscattered seed photons decreases very strongly with the source Lorentz factor, thus bright GRB optical counterparts cannot arise from internal pairs if the afterglow Lorentz factor is above several hundreds.« less

  7. Optical flashes from internal pairs formed in gamma-ray burst afterglows

    SciTech Connect

    Panaitescu, A.

    2015-06-09

    We develop a numerical formalism for calculating the distribution with energy of the (internal) pairs formed in a relativistic source from unscattered MeV–TeV photons. For gamma-ray burst (GRB) afterglows, this formalism is more suitable if the relativistic reverse shock that energizes the ejecta is the source of the GeV photons. The number of pairs formed is set by the source GeV output (calculated from the Fermi-LAT fluence), the unknown source Lorentz factor, and the unmeasured peak energy of the LAT spectral component. We show synchrotron and inverse-Compton light curves expected from pairs formed in the shocked medium and identify some criteria for testing a pair origin of GRB optical counterparts. Pairs formed in bright LAT afterglows with a Lorentz factor in the few hundreds may produce bright optical counterparts ($R\\lt 10$) lasting for up to one hundred seconds. As a result, the number of internal pairs formed from unscattered seed photons decreases very strongly with the source Lorentz factor, thus bright GRB optical counterparts cannot arise from internal pairs if the afterglow Lorentz factor is above several hundreds.

  8. Recombination of polycyclic aromatic hydrocarbon photoions with electrons in a flowing afterglow plasma.

    PubMed

    Novotný, O; Sivaraman, B; Rebrion-Rowe, C; Travers, D; Biennier, L; Mitchell, J B A; Rowe, B R

    2005-09-08

    A new technique, flowing afterglow with photoions (FIAPI), has been developed to measure the rate coefficient for the recombination of complex ions, and, in particular, polycyclic aromatic hydrocarbon (PAH) cations with electrons. The method is based on the flowing afterglow Langmuir probe - mass spectrometer apparatus at the University of Rennes I. A helium plasma is generated by a microwave discharge in a He buffer gas and downstream, a small amount of argon gas is injected to destroy any helium metastables. A very small amount of neutral PAH molecules is added to the afterglow plasma by evaporation from a plate coated with the PAH to be studied. PAH ions are then produced by photoionization of the parent molecule using a pulsed UV laser (157 nm). The laser beam is oriented along the flow tube and so a constant spatial concentration of photoions is obtained. The electron concentration along the flow tube is measured by means of a movable Langmuir probe. Ion concentration decay in time is measured at a fixed position using a quadrupole mass spectrometer which is triggered by the laser pulse. The recombination of anthracene and pyrene cations has been studied using this technique and we have found a recombination rate of (2.4 +/- 0.8) x 10(-6) cm(3) s(-1) for anthracene and (4.1 +/- 1.2) x 10(-6) cm(3) s(-1) for pyrene.

  9. Recombination of polycyclic aromatic hydrocarbon photoions with electrons in a flowing afterglow plasma

    SciTech Connect

    Novotny, O.; Sivaraman, B.; Rebrion-Rowe, C.; Travers, D.; Biennier, L.; Mitchell, J.B.A.; Rowe, B.R.

    2005-09-08

    A new technique, flowing afterglow with photoions (FIAPI), has been developed to measure the rate coefficient for the recombination of complex ions, and, in particular, polycyclic aromatic hydrocarbon (PAH) cations with electrons. The method is based on the flowing afterglow Langmuir probe - mass spectrometer apparatus at the University of Rennes I. A helium plasma is generated by a microwave discharge in a He buffer gas and downstream, a small amount of argon gas is injected to destroy any helium metastables. A very small amount of neutral PAH molecules is added to the afterglow plasma by evaporation from a plate coated with the PAH to be studied. PAH ions are then produced by photoionization of the parent molecule using a pulsed UV laser (157 nm). The laser beam is oriented along the flow tube and so a constant spatial concentration of photoions is obtained. The electron concentration along the flow tube is measured by means of a movable Langmuir probe. Ion concentration decay in time is measured at a fixed position using a quadrupole mass spectrometer which is triggered by the laser pulse. The recombination of anthracene and pyrene cations has been studied using this technique and we have found a recombination rate of (2.4{+-}0.8)x10{sup -6} cm{sup 3} s{sup -1} for anthracene and (4.1{+-}1.2)x10{sup -6} cm{sup 3} s{sup -1} for pyrene.

  10. Ar^+ recombination with negative ions in a flowing afterglow: A new approach.

    NASA Astrophysics Data System (ADS)

    Miller, Thomas M.; Viggiano, A. A.

    2006-05-01

    Ion-ion recombination (mutual neutralization) has been previously studied in a flowing-afterglow Langmuir-probe apparatus, using the probe to measure the positive-ion and negative-ion densities as a function of distance (time) along the flow tube axis.^1 A different approach has been taken in the present work, applicable to Ar^+ (or Kr^+ and Xe^+) recombination reactions. A flowing electron-Ar^+ afterglow plasma is first established, and the ambipolar diffusion frequency is measured. Then, an electron attaching gas is added to the afterglow, and the electron attachment rate constant and product ion branching fractions are measured in the usual manner.^2 Finally, the reactant gas concentration is reduced enough that the attachment reaction has not gone to completion by the end of the flow tube. Modeling of the diffusion, attachment, and recombination processes allows us to determine rate constants for each negative ion type recombining with Ar^+. For example, Ar^+ neutralized by Cl^-, Cl2^-, and CCl2O^- produced in attachment to oxalyl chloride,^2 shows that Cl2^- recombines at about half the rate constant of CCl2O^-, and Cl^- + Ar^+ recombination is negligible. ^1D. Smith and N. G. Adams, in Physics of Ion-Ion and Electron-Ion Collisions, Ed. F. Brouillard and J. W. McGowan (Plenum, New York, 1983). ^2J. M. Van Doren, T. M. Miller, and A. A. Viggiano, J. Chem. Phys. (submitted).

  11. Recombination of polycyclic aromatic hydrocarbon photoions with electrons in a flowing afterglow plasma

    NASA Astrophysics Data System (ADS)

    Novotný, O.; Sivaraman, B.; Rebrion-Rowe, C.; Travers, D.; Biennier, L.; Mitchell, J. B. A.; Rowe, B. R.

    2005-09-01

    A new technique, flowing afterglow with photoions (FIAPI), has been developed to measure the rate coefficient for the recombination of complex ions, and, in particular, polycyclic aromatic hydrocarbon (PAH) cations with electrons. The method is based on the flowing afterglow Langmuir probe - mass spectrometer apparatus at the University of Rennes I. A helium plasma is generated by a microwave discharge in a He buffer gas and downstream, a small amount of argon gas is injected to destroy any helium metastables. A very small amount of neutral PAH molecules is added to the afterglow plasma by evaporation from a plate coated with the PAH to be studied. PAH ions are then produced by photoionization of the parent molecule using a pulsed UV laser (157 nm). The laser beam is oriented along the flow tube and so a constant spatial concentration of photoions is obtained. The electron concentration along the flow tube is measured by means of a movable Langmuir probe. Ion concentration decay in time is measured at a fixed position using a quadrupole mass spectrometer which is triggered by the laser pulse. The recombination of anthracene and pyrene cations has been studied using this technique and we have found a recombination rate of (2.4±0.8)×10-6cm3s-1 for anthracene and (4.1±1.2)×10-6cm3s-1 for pyrene.

  12. Kinematics of Gamma-Ray Burst and their Relationship to Afterglows

    SciTech Connect

    Salmonson, J D

    2001-12-17

    A strong correlation is reported between gamma-ray burst (GRB) pulse lags and afterglow jet-break times for the set of bursts (seven) with known redshifts, luminosities, pulse lags, and jet-break times. This may be a valuable clue toward understanding the connection between the burst and afterglow phases of these events. The relation is roughly linear (i.e. doubling the pulse lag in turn doubles the jet break time) and thus implies a simple relationship between these quantities. We suggest that this correlation is due to variation among bursts of emitter Doppler factor. Specifically, an increased speed or decreased angle of velocity, with respect to the observed line-of-site, of burst ejecta will result in shorter perceived pulse lags in GRBs as well as quicker evolution of the external shock of the afterglow to the time when the jet becomes obvious, i.e. the jet-break time. Thus this observed variation among GRBs may result from a perspective effect due to different observer angles of a morphologically homogeneous populations of GRBs. Also, a conjecture is made that peak luminosities not only vary inversely with burst timescale, but also are directly proportional to the spectral break energy. If true, this could provide important information for explaining the source of this break.

  13. GRB 081029: A Gamma-Ray Burst with a Multi-Component Afterglow

    NASA Technical Reports Server (NTRS)

    Holland, Stephen T.; DePasquale, Massimiliano; Mao, Jirong; Sakamoto, Taka; Shady, Patricia; Covino, Stefano; Yi-Zhong, Fan; Zhi-Ping, Jin; D'Avanzo, Paolo; Antonelli, Angelo; D'Elia, Valerio; Chincarini, Guido; Fiore, Fabrizio; Pandey, Shashi Bhushan

    2011-01-01

    We present an analysis of the unusual optical light curve of the gamma-ray burst GRB 081029, a long-soft burst with a redshift of z = 3.8479. We combine X-ray and optical observations from the Swift X-Ray Telescope and the Swift UltraViolet Optical Telescope with ground-based optical and infrared data obtained using the REM and ROTSE telescopes to construct a detailed data set extending from 86 s to approx. 100000 s after the BAT trigger. Our data cover a wide energy range, from 10 keV to 0.77 eV (1.24 A to 16000 A). The X-ray afterglow shows a shallow initial decay followed by a rapid decay starting at about 18000 s. The optical and infrared afterglow, however, shows an uncharacteristic rise at about 5000 s that does not correspond to any feature in the X-ray light curve. Our data are not consistent with synchrotron radiation from a jet interacting with an external medium, a two-component jet, or continuous energy injection from the central engine. We find that the the optical light curves can be broadly explained by a collision between two ejecta shells within a two-component jet. A growing number of gamma-ray burst afterglows are consistent with complex jets, which suggests that some (or all) gamma-ray burst jets are complex and will require detailed modelling to fully understand them.

  14. The Achromatic Light Curve of the Optical Afterglow of GRB 030226 at a Redshift of z Approximately 2

    NASA Technical Reports Server (NTRS)

    Klose, S.; Greiner, J.; Rau, A.; Henden, A. A.; Hartmann, D. H.; Zeh, A.; Masetti, N.; Guenther, E.; Stecklum, B.; Lindsay, K.

    2003-01-01

    Abstract. We report on optical and near-infrared (NIR) follow-up observations of the afterglow of GRB 030226, mainly performed with the telescopes at ESO La Silla and Paranal, with additional data obtained at other places. Our first observations started 0.2 days after the burst when the afterglow was at a magnitude of R approximately equal to 19 . One week later the magnitude of the afterglow had fallen to R=25, and at two weeks after the burst it could no longer be detected (R > 26). Our VLT blueband spectra show two absorption line systems at redshifts z = 1.962 +/- 0.001 and at z = 1.986 +/- 0.001, placing the redshift of the burster close to 2. Within our measurement errors no evidence for variations in the line strengths has been found between 0.2 and 1.2 days after the burst. An overabundance of alpha-group elements might indicate that the burst occurred in a chemically young interstellar region shaped by the nucleosynthesis from type II supernovae. The spectral slope of the afterglow shows no signs for cosmic dust along the line of sight in the GRB host galaxy, which itself remained undetected (R > 26.2). At the given redshift no supernova component affected the light from the GRB afterglow, so that the optical transient was essentially only powered by the radiation from the GRB fireball, allowing for a detailed investigation of the color evolution of the afterglow light. In our data set no obvious evidence for color changes has been found before, during, or after the smooth break in the light curve approximately 1 day after the burst. In comparison with investigations by others, our data favor the interpretation that the afterglow began to develop into a homogeneous interstellar medium before the break in the light curve became apparent.

  15. Electrical characterization of the flowing afterglow of N2 and N2/O2 microwave plasmas at reduced pressure

    NASA Astrophysics Data System (ADS)

    Afonso Ferreira, J.; Stafford, L.; Leonelli, R.; Ricard, A.

    2014-04-01

    A cylindrical Langmuir probe was used to analyze the spatial distribution of the number density of positive ions and electrons as well as the electron energy distribution function (EEDF) in the flowing afterglow of a 6 Torr N2 and N2/O2 plasma sustained by a propagating electromagnetic surface wave in the microwave regime. In pure N2 discharges, ion densities were in the mid 1014 m-3 in the pink afterglow and in the mid 1012 m-3 early in the late afterglow. In both pink and late afterglows, the ion population was much higher than the electron population, indicating non-macroscopically neutral media. The EEDF was close to a Maxwellian with an electron temperature of 0.5 ± 0.1 eV, except in the pink afterglow where the temperature rose to 1.1 ± 0.2 eV. This latter behavior is ascribed to N2 vibration-vibration pumping in the pink afterglow that increases the concentration of high N2 vibrational states and thus rises the electron temperature by vibration-electron collisions. After addition of small amounts of O2 in the nominally pure N2 discharge, the charged particles densities and average electron energy first strongly increased and then decreased with increasing O2 concentration. Based on these data and the evolution of the N2+(B) band emission intensities, it is concluded that a significant change in the positive ion composition of the flowing afterglow occurs, going from N2+ in nominally pure N2 discharges to NO+ after addition of trace amounts of O2 in N2.

  16. Chemical abundances associated with gamma-ray bursts: nucleosynthesis in afterglows

    NASA Astrophysics Data System (ADS)

    Hu, Tao; Wang, Min

    2014-03-01

    Gamma-ray burst (GRB) ejecta carries huge amounts of energy expanding into the surrounding medium and heats up these materials, making it possible that nucleosynthesis can take place in such hot sites in afterglow stage. Here, we study possible changes in chemical abundances in the GRB afterglow processes of Wolf-Rayet (WR) star wind environments (Case A) and constant density surroundings (Case B). We find that the light element of lithium-beryllium-boron could occur in the afterglows via He+He process and spallation reactions. Some isotopes of F, Ne, Mg, Al, Si, P, S and Fe-group elements are also new species formed in the afterglows via proton-, neutron- and α-capture. The results show that the nucleosynthetic yields might be a diagnostic of the GRB's ambient environment. Our calculations indicate that Mg, Al, Si, P, Cr, Mn, Fe and Co have trended to appear in Case A, while Ne, Ti and Ni trend to occur in Case B. Furthermore, although some species have occurred both in Cases A and B, their mass fractions are quite different in these two cases. Here, we show that the mass fractions of 7Li, 7Be, 24Mg and 30Si are higher in Case A than that in Case B, but 18F gives an opposite conclusion. Nucleosynthetic outputs might also be an indice to estimate the luminosity-temperature relation factor β. In this study, when β reduces, the mass abundances of 11B and 20Ne are higher in Case B than that in Case A; in contrast, as the β becomes larger, this trend would be reversed; therefore, perhaps we could select the above elements as the indicators to estimate the properties of the surroundings around the GRBs. We also suggest that the spectroscopic observations of a GRB afterglow could only reveal the nucleosynthetic outputs from the interaction site between the GRB jet and its ambient matter, but could not represent the original composition of the pre-GRB surrounding medium.

  17. Gamma-ray burst afterglows as probes of their host galaxies and the cosmos

    NASA Astrophysics Data System (ADS)

    Cucchiara, Antonino

    2010-12-01

    Gamma-ray Bursts (GRBs) represent the sole class of catastrophic phenomena seen over almost the entire history of the Universe. Their extreme luminosities in high energy gamma-ray radiation make them readily detectable, even with relatively small satellite-based detectors, out to the earliest cosmic epochs. Moreover, the brilliance of their fading afterglow light, routinely observed in X-ray, optical, near-infrared, and radio wavelengths, allows them to be exploited -- for hours, days, or weeks -- as cosmic lighthouses, probing the conditions of gas and dust along the line of sight, through their host galaxies and the cosmos at large. Since the November 2004 launch of Swift, this GRB-focused NASA mission has discovered more than 500 GRBs, in almost all cases reporting the burst coordinates to ground-based observers within seconds of the event. The availability of prompt burst positions from Swift, combined with promptly-reported flux measurements from instruments on Swift and an array of ground-based robotic telescopes, have enabled targeted spectroscopic campaigns that have gathered detailed observations of the young, bright afterglows of hundreds of these events. This thesis reports the results of my own efforts over the past 5 years, analyzing imaging and spectroscopic observations of Swift-detected GRBs as triggered according to my own requests, or as gathered from public data archives. In Chapter 2, I discuss our follow-up campaign for GRB090429B, one of our best "extreme redshift" (z > 8) candidates. This burst followed closely on the spectroscopicallyconfirmed z = 8.2 GRB090423, and our multiwavelength observations and SED modeling demonstrate the value and limitation of such studies, in cases where a spectroscopic redshift cannot be gathered in a timely fashion. I also address the importance of such extreme-redshift events from a cosmological perspective. In Chapter 3, I use high-resolution GRB afterglow spectra to study the properties of intervening

  18. DISCOVERY OF THE VERY RED NEAR-INFRARED AND OPTICAL AFTERGLOW OF THE SHORT-DURATION GRB 070724A

    SciTech Connect

    Berger, E.; Cenko, S. B.; Fox, D. B.; Cucchiara, A.

    2009-10-10

    We report the discovery of the near-infrared and optical afterglow of the short-duration gamma-ray burst GRB 070724A. The afterglow is detected in iJHK{sub s} observations starting 2.3 hr after the burst with K{sub s} = 19.59 +- 0.16 mag and i = 23.79 +- 0.07 mag, but is absent in images obtained 1.3 yr later. Fading is also detected in the K{sub s} band between 2.8 and 3.7 hr at a 4sigma significance level. The optical/near-IR spectral index, beta{sub O,NIR} approx -2, is much redder than expected in the standard afterglow model, pointing to either significant dust extinction, A {sup host} {sub V} approx 2 mag, or a non-afterglow origin for the near-IR emission. The case for extinction is supported by a shallow optical to X-ray spectral index, consistent with the definition for 'dark bursts', and a normal near-IR to X-ray spectral index. Moreover, a comparison to the optical discovery magnitudes of all short GRBs with optical afterglows indicates that the near-IR counterpart of GRB 070724A is one of the brightest to date, while its observed optical emission is one of the faintest. In the context of a non-afterglow origin, the near-IR emission may be dominated by a mini-supernova (mini-SN), leading to an estimated ejected mass of M approx 10{sup -4} M {sub sun} and a radioactive energy release efficiency of f approx 5 x 10{sup -3} (for v approx 0.3c). However, the mini-SN model predicts a spectral peak in the UV rather than near-IR, suggesting that this is either not the correct interpretation or that the mini-SN models need to be revised. Finally, the afterglow coincides with a star-forming galaxy at z = 0.457, previously identified as the host based on its coincidence with the X-ray afterglow position (approx2'' radius). Our discovery of the optical/near-IR afterglow makes this association secure, and furthermore localizes the burst to the outskirts of the galaxy, with an offset of 4.8 +- 0.1 kpc relative to the host center. At such a large offset, the possible

  19. Synthesis of ZnS:Ag,Co water-soluble blue afterglow nanoparticles and application in photodynamic activation

    NASA Astrophysics Data System (ADS)

    Ma, Lun; Zou, Xiaoju; Hossu, Marius; Chen, Wei

    2016-08-01

    Silver and cobalt co-doped ZnS (ZnS:Ag,Co) water-soluble afterglow nanoparticles were synthesized using a wet chemistry method followed by aging at room temperature. The nanoparticles had a cubic zinc blende structure with average sizes of approximately 4 nm and emitted a blue fluorescence emission centered at 441 nm due to radiative transitions from surface defects to Ag+ luminescent centers. Intense afterglow emission peaking at 475 nm from the obtained nanoparticles was observed and was red-shifted compared to the fluorescence emission peak. X-ray photoelectron spectroscopy revealed a large increase of O/S ratio, indicating a surface oxidation process during aging. The S vacancies produced accordingly may contribute to form more electron traps and enhance afterglow. The ZnS:Ag,Co afterglow nanoparticles have a very low dark-toxicity and are applied as a light source for photodynamic therapy activation by conjugating with protoporphyrin together. Our preliminary study has shown that the ZnS:Ag,Co afterglow nanoparticles can significantly reduce the x-ray dosage used in activation and thus may be a very promising candidate for future x-ray excited photodynamic therapy in deep cancer treatment.

  20. Looking Into the Fireball: ROTSE-III and Swift Observations of Early Gamma-ray Burst Afterglows

    NASA Astrophysics Data System (ADS)

    Rykoff, E. S.; Aharonian, F.; Akerlof, C. W.; Ashley, M. C. B.; Barthelmy, S. D.; Flewelling, H. A.; Gehrels, N.; Göǧüş, E.; Güver, T.; Kiziloǧlu, Ü.; Krimm, H. A.; McKay, T. A.; Özel, M.; Phillips, A.; Quimby, R. M.; Rowell, G.; Rujopakarn, W.; Schaefer, B. E.; Smith, D. A.; Vestrand, W. T.; Wheeler, J. C.; Wren, J.; Yuan, F.; Yost, S. A.

    2009-09-01

    We report on a complete set of early optical afterglows of gamma-ray bursts (GRBs) obtained with the Robotic Optical Transient Search Experiment (ROTSE-III) telescope network from 2005 March through 2007 June. This set is comprised of 12 afterglows with early optical and Swift/X-Ray Telescope observations, with a median ROTSE-III response time of 45 s after the start of γ-ray emission (8 s after the GCN notice time). These afterglows span 4 orders of magnitude in optical luminosity, and the contemporaneous X-ray detections allow multi-wavelength spectral analysis. Excluding X-ray flares, the broadband synchrotron spectra show that the optical and X-ray emission originate in a common region, consistent with predictions of the external forward shock in the fireball model. However, the fireball model is inadequate to predict the temporal decay indices of the early afterglows, even after accounting for possible long-duration continuous energy injection. We find that the optical afterglow is a clean tracer of the forward shock, and we use the peak time of the forward shock to estimate the initial bulk Lorentz factor of the GRB outflow, and find 100 lsim Γ0 lsim 1000, consistent with expectations.

  1. A CORRELATED STUDY OF OPTICAL AND X-RAY AFTERGLOWS OF GRBs

    SciTech Connect

    Li, Liang; Ryde, Felix; Wu, Xue-Feng; Huang, Yong-Feng; Tang, Qing-Wen; Geng, Jin-Jun; Wang, Xiang-Gao; Liang, En-Wei; Liang, Yun-Feng; Zhang, Bin-Bin; Wang, Yu; Wei, Jian-Yan; Zhang, Bing E-mail: liang.li@fysik.su.se

    2015-05-20

    We study an extensive sample of 87 gamma-ray bursts (GRBs) for which there are well-sampled and simultaneous optical and X-ray light curves. We extract the cleanest possible signal of the afterglow component and compare the temporal behaviors of the X-ray light curve, observed by Swift XRT, and optical data, observed by UVOT and ground-based telescopes for each individual burst. Overall we find that 62% of the GRBs are consistent with the standard afterglow model. When more advanced modeling is invoked, up to 91% of the bursts in our sample may be consistent with the external-shock model. A large fraction of these bursts are consistent with occurring in a constant interstellar density medium (61%) while only 39% of them occur in a wind-like medium. Only nine cases have afterglow light curves that exactly match the standard fireball model prediction, having a single power-law decay in both energy bands that are observed during their entire duration. In particular, for the bursts with chromatic behavior, additional model assumptions must be made over limited segments of the light curves in order for these bursts to fully agree with the external-shock model. Interestingly, for 54% of the X-ray and 40% of the optical band observations, the end of the shallow decay (t{sup ∼−0.5}) period coincides with the jet-break (t{sup ∼−p}) time, causing an abrupt change in decay slope. The fraction of the burst that is consistent with the external-shock model is independent of the observational epochs in the rest frame of GRBs. Moreover, no cases can be explained by the cooling frequency crossing the X-ray or optical band.

  2. GRB 110731A: Early Afterglow in Stellar Wind Powered By a Magnetized Outflow

    NASA Astrophysics Data System (ADS)

    Fraija, N.

    2015-05-01

    One of the most energetic gamma-ray bursts, GRB 110731A, was observed from an optical to GeV energy range. Previous analysis of the prompt phase revealed similarities between the Large Area Telescope (LAT) bursts observed by Fermi: (1) a delayed onset of the high-energy emission (\\gt 100 MeV), (2) a short-lasting bright peak at later times, and (3) a temporally extended component from this phase, lasting hundreds of seconds. Additionally to the prompt phase, multiwavelength observations over different epochs showed that the spectral energy distribution was better fitted by a wind afterglow model. We present a leptonic model based on an early afterglow that evolves in a stellar wind of its progenitor. We apply this model to interpret the temporally extended LAT emission and the brightest LAT peak exhibited by the prompt phase of GRB 110731A. Additionally, using the same set of parameters, we describe the multiwavelength afterglow observations. The origin of the temporally extended LAT, X-ray, and optical flux is explained through synchrotron radiation from the forward shock (FS) and the brightest LAT peak is described, evoking the synchrotron self-Compton emission from the reverse shock (RS). The bulk Lorentz factor required in this model (Γ ≃ 520) lies in the range of values demanded for most LAT-detected GRBs. We show that the strength of the magnetic field in the RS region is ∼50 times stronger than that in the FS region. This result suggests that, for GRB 110731A, the central engine is likely entrained with strong magnetic fields.

  3. A HIGH SIGNAL-TO-NOISE RATIO COMPOSITE SPECTRUM OF GAMMA-RAY BURST AFTERGLOWS

    SciTech Connect

    Christensen, L.; Fynbo, J. P. U.; Prochaska, J. X.; Jakobsson, P.

    2011-02-01

    We present a composite spectrum of 60 long duration gamma-ray burst (GRB) afterglows with redshifts in the range 0.35 < z < 6.7 observed with low-resolution optical spectra. The composite spectrum covers the wavelength range 700-6600 A in the rest frame and has a mean signal-to-noise ratio of 150 per 1 A pixel and reaches a maximum of {approx}300 in the range 2500-3500 A. Equivalent widths are measured from metal absorption lines from the Ly{alpha} line to {approx}5200 A, and associated metal and hydrogen lines are identified between the Lyman break and Ly{alpha} line. The average transmission within the Lyman forest is consistent with that found along quasar lines of sight. We find a temporal variation in fine-structure lines when dividing the sample into bursts observed within 2 hr from their trigger and those observed later. Other lines in the predominantly neutral gas show variations too, but this is most likely a random effect caused by weighting of individual strong absorption lines and which mimics a temporal variation. Bursts characterized with high- or low-prompt GRB energy release produce afterglows with similar absorption line strengths, and likewise for bursts with bright or faint optical afterglows. Bursts defined as dark from their optical to X-ray spectral index have stronger absorption lines relative to the optically bright bursts. The composite spectrum has strong Ca II and Mg II absorption lines as commonly found in dusty galaxies, however, we find no evidence for dust or a significant molecular content based on the non-detection of diffuse interstellar bands. Compared to starburst galaxy spectra, the GRB composite has much stronger fine-structure lines, while metal absorption lines are weaker.

  4. GRB 081029: A Gamma-Ray Burst with a Multi-Component Afterglow

    NASA Technical Reports Server (NTRS)

    Holland, Stephen T.; De Pasquale, Massimiliano; Mao, Jirong; Sakamoto, Takanori; Schady, Patricia; Covino, Stefano; Fan, Yi-Zhong; Jin, Zhi-Ping; D'Avanzo, Paolo; Antonelli, Angelo; D'Elia, Valerio; Ohincarini, Guido; Fiore, Fabrizio; Pandey, Shashi Bhushan; Cobb, Bethany E.

    2012-01-01

    We present an analysis of the unusual optical light curve of the gamma-ray burst GRB 081029, a long-soft burst with a redshift of z = 3.8479. We combine X-ray and optical observations from the Swift X-Ray Telescope and the Swift Ultra Violet/Optical Telescope with ground-based optical and infrared data obtained using the REM, ROTSE, and CTIO 1.3-m telescopes to construct a detailed data set extending from 86 s to approx.100,000 s after the BAT trigger. Our data covers a wide energy range, from 10 keV to 0.77 eV (1.24 A to 16000 A). The X-ray afterglow shows a shallow initial decay followed by a rapid decay starting at about 18,000 s. The optical and infrared afterglow, however, shows an uncharacteristic rise at about 3000 s that does not correspond to any feature in the X-ray light curve. Our data are not consistent with synchrotron radiation from a jet interacting with an external medium, a two-component jet, or continuous energy injection from the central engine. We find that the optical light curves can be broadly explained by a collision between two ejecta shells within a two-component jet. A growing number of gamma-ray burst afterglows are consistent with complex jets, which suggests that some (or all) gamma-ray burst jets are complex and will require detailed modelling to fully understand them.injection

  5. Evidence for a Canonical GRB Afterglow Light Curve in the Swift/XRT Data

    SciTech Connect

    Nousek, J.A.; Kouveliotou, C.; Grupe, D.; Page, K.; Granot, J.; Ramirez-Ruiz, E.; Patel, S.K.; Burrows, D.N.; Mangano, V.; Barthelmy, S.; Beardmore, A.P.; Campana, S.; Capalbi, M.; Chincarini, G.; Cusumano, G.; Falcone, A.D.; Gehrels, N.; Giommi, P.; Goad, M.; Godet, O.; Hurkett, C.; /Penn State U., Astron. Astrophys. /NASA, Marshall /Leicester U. /KIPAC, Menlo Park /Princeton, Inst. Advanced Study /NASA, Marshall /IASF, Palermo /Brera Observ. /Frascati /Milan Bicocca U. /NASA, Goddard

    2005-08-17

    We present new observations of the early X-ray afterglows of the first 27 gamma-ray bursts (GRBs) detected with the Swift X-ray Telescope (XRT). The early X-ray afterglows show a canonical behavior, where the light curve broadly consists of three distinct power law segments: (1) an initial very steep decay ({infinity} t{sup -a} with 3 {approx}< a{sub 1} {approx}< 5) , followed by (2) a very shallow decay (0.2 {approx}< a{sub 2} {approx}< 0.8), and finally (3) a somewhat steeper decay (1 {approx}< a{sub 3} {approx}< 1.5). These power law segments are separated by two corresponding break times, 300 s {approx}< t{sub break,1} {approx}< 500 s and 10{sup 3} s {approx}< t{sub break,2} {approx}< 10{sup 4} s. On top of this canonical behavior of the early X-ray light curve, many events have superimposed X-ray flares, which are most likely caused by internal shocks due to long lasting sporadic activity of the central engine, up to several hours after the GRB. We find that the initial steep decay is consistent with it being the tail of the prompt emission, from photons that are radiated at large angles relative to our line of sight. The first break in the light curve (t{sub break,1}) takes place when the forward shock emission becomes dominant, with the intermediate shallow flux decay (a{sub 2}) likely caused by the continuous energy injection into the external shock. When this energy injection stops, a second break is then observed in the light curve (t{sub break,2}). This energy injection increases the energy of the afterglow shock by at least a factor of f {approx}> 4, and augments the already severe requirements for the efficiency of the prompt gamma-ray emission.

  6. The plateau phase of gamma-ray burst afterglows in the thick-shell scenario

    NASA Astrophysics Data System (ADS)

    Leventis, K.; Wijers, R. A. M. J.; van der Horst, A. J.

    2014-01-01

    We present analytic calculations of synchrotron radiation from the forward and the reverse shock of gamma-ray burst blast waves, in the thick-shell scenario (i.e. when the reverse shock is relativistic). We show that this scenario can naturally account for the plateau phase, observed early in the afterglows of about half the bursts detected by Swift. We generalize our approach to include power-law luminosity of the central engine and show that when radiation from both regions (forward and reverse shock) is taken into account, a wide range of possibilities emerge, including chromatic and achromatic breaks, frequency-dependent spectral evolution during the injection break and widely varying decay indices in different bands. For both the forward and the reverse shock, we derive formulas for the spectral parameters and the observed flux in different power-law segments of the spectrum, as a function of observer time. We explore the Fb-tb relation (between the observed time of the end of the plateau phase and the flux at that point) in the framework of the presented model and show that model predictions favour the reverse shock as the dominant source of emission in both optical and X-rays. As case studies, we present simultaneous fits to X-ray and optical/IR afterglow data of GRB 080928 and GRB 090423. We identify the end of the plateau phase with the cessation of energy injection and infer the corresponding upper limits to central-engine activity, which are about 1 h for the former and 1.5 h for the latter. We conclude that smooth energy injection through the reverse shock is a plausible explanation for the plateau phase of gamma-ray burst afterglows. During that phase, radiation from the reverse shock is likely to be important, or even dominant, and should be taken into account when fitting model parameters to observations.

  7. The Supercritical Pile Gamma-Ray Burst Model: The GRB Afterglow Steep Decline and Plateau Phase

    NASA Technical Reports Server (NTRS)

    Sultana, Joseph; Kazanas, D.; Mastichiadis, A.

    2013-01-01

    We present a process that accounts for the steep decline and plateau phase of the Swift X-Ray Telescope (XRT) light curves, vexing features of gamma-ray burst (GRB) phenomenology. This process is an integral part of the "supercritical pile" GRB model, proposed a few years ago to account for the conversion of the GRB kinetic energy into radiation with a spectral peak at E(sub pk) is approx. m(sub e)C(exp 2). We compute the evolution of the relativistic blast wave (RBW) Lorentz factor Gamma to show that the radiation-reaction force due to the GRB emission can produce an abrupt, small (approx. 25%) decrease in Gamma at a radius that is smaller (depending on conditions) than the deceleration radius R(sub D). Because of this reduction, the kinematic criticality criterion of the "supercritical pile" is no longer fulfilled. Transfer of the proton energy into electrons ceases and the GRB enters abruptly the afterglow phase at a luminosity smaller by approx. m(sub p)/m(sub e) than that of the prompt emission. If the radius at which this slow-down occurs is significantly smaller than R(sub D), the RBW internal energy continues to drive the RBW expansion at a constant (new) Gamma and its X-ray luminosity remains constant until R(sub D) is reached, at which point it resumes its more conventional decay, thereby completing the "unexpected" XRT light curve phase. If this transition occurs at R is approx. equal to R(sub D), the steep decline is followed by a flux decrease instead of a "plateau," consistent with the conventional afterglow declines. Besides providing an account of these peculiarities, the model suggests that the afterglow phase may in fact begin before the RBW reaches R is approx. equal to R(sub D), thus providing novel insights into GRB phenomenology.

  8. Managing GRB afterglows optical/IR observations in the web 2.0 era

    NASA Astrophysics Data System (ADS)

    Ricci, D.; Nicastro, L.

    2013-07-01

    We present an overview of top internet technologies that can be used to build webtools and rich internet applications for astronomy. The aim is to simplify the data handling, reduction and access, in particular of optical/infrared images collected by traditional, automatic or robotic telescopes. These tools are particularly suitable for real-time management of GRB afterglow observations. Using these technologies we are developing a web-based images database management system. We present available features and discuss further improvements to the mentioned system.

  9. Magnetic scavengers as carriers of analytes for flowing atmospheric pressure afterglow mass spectrometry (FAPA-MS).

    PubMed

    Cegłowski, Michał; Kurczewska, Joanna; Smoluch, Marek; Reszke, Edward; Silberring, Jerzy; Schroeder, Grzegorz

    2015-09-07

    In this paper, a procedure for the preconcentration and transport of mixtures of acids, bases, and drug components to a mass spectrometer using magnetic scavengers is presented. Flowing atmospheric pressure afterglow mass spectrometry (FAPA-MS) was used as an analytical method for identification of the compounds by thermal desorption from the scavengers. The proposed procedure is fast and cheap, and does not involve time-consuming purification steps. The developed methodology can be applied for trapping harmful substances in minute quantities, to transport them to specialized, remotely located laboratories.

  10. Recombination of H3(+) and D3(+) Ions in a Flowing Afterglow Plasma

    NASA Technical Reports Server (NTRS)

    Gougousi, T.; Johnsen, R.; Golde, M. F.

    1995-01-01

    The analysis of flowing afterglow plasmas containing H3(+) or D3(+) ions indicates that the de-ionization of such plasmas does not occur by simple dissociative recombination of ions with electrons. An alternative model of de-ionization is proposed in which electrons are captured into H3(**) auto-ionization Rydberg states that are stabilized by collisional mixing of the Rydberg molecules' angular momenta. The proposed mechanism would enable de-ionization to occur without the need for dissociative recombination by the mechanisms of potential-surface crossings.

  11. Decay phases of Swift X-ray afterglows and the forward-shock model.

    PubMed

    Panaitescu, A

    2007-05-15

    The X-ray flux of the gamma-ray burst (GRB) afterglows monitored by the Swift satellite from January 2005 to July 2006 displays one to four phases of flux power-law decay. In chronological order, they are: the GRB tail, the 'hump', the standard decay and the post-jet-break decay. More than half of the GRB tails can be identified with the large-angle emission produced during the burst (but arriving later at observer). The remaining, slower GRB tails imply that the gamma-ray mechanism continues to radiate after the burst, as also suggested by the frequent occurrence of X-ray flares during the burst tail. The several GRB tails exhibiting a slow unbroken power-law decay until 100ks must be attributed to the forward shock. In fact, the decay of most GRB tails is also consistent with that of the forward-shock emission from a narrow jet. The X-ray light-curve hump may be due to an increase of the kinetic energy per solid angle of the forward-shock region visible to the observer, caused by either the transfer of energy from ejecta to the forward shock or the emergence of the emission from an outflow seen from a location outside the jet opening. The decay following the X-ray light-curve hump is consistent with the emission from an adiabatic blast wave but, contrary to expectations, the light-curve decay index and spectral slope during this phase are not correlated. The X-ray light curves of two dozens X-ray afterglows that followed for more than a week do not exhibit a jet break, in contrast with the behaviour of pre-Swift optical afterglows, which displayed jet breaks at 0.5-2 days. Nevertheless, the X-ray light curves of several Swift afterglows show a second steepening break at 0.4-3 days that is consistent with the break expected for a jet when its edge becomes visible to the observer.

  12. The mysterious optical afterglow spectrum of GRB 140506A at z = 0.889

    NASA Astrophysics Data System (ADS)

    Fynbo, J. P. U.; Krühler, T.; Leighly, K.; Ledoux, C.; Vreeswijk, P. M.; Schulze, S.; Noterdaeme, P.; Watson, D.; Wijers, R. A. M. J.; Bolmer, J.; Cano, Z.; Christensen, L.; Covino, S.; D'Elia, V.; Flores, H.; Friis, M.; Goldoni, P.; Greiner, J.; Hammer, F.; Hjorth, J.; Jakobsson, P.; Japelj, J.; Kaper, L.; Klose, S.; Knust, F.; Leloudas, G.; Levan, A.; Malesani, D.; Milvang-Jensen, B.; Møller, P.; Nicuesa Guelbenzu, A.; Oates, S.; Pian, E.; Schady, P.; Sparre, M.; Tagliaferri, G.; Tanvir, N.; Thöne, C. C.; de Ugarte Postigo, A.; Vergani, S.; Wiersema, K.; Xu, D.; Zafar, T.

    2014-12-01

    Context. Gamma-ray burst (GRB) afterglows probe sightlines to star-forming regions in distant star-forming galaxies. Here we present a study of the peculiar afterglow spectrum of the z = 0.889Swift GRB 140506A. Aims: Our aim is to understand the origin of the very unusual properties of the absorption along the line of sight. Methods: We analyse spectroscopic observations obtained with the X-shooter spectrograph mounted on the ESO/VLT at two epochs 8.8 h and 33 h after the burst, and with imaging from the GROND instrument. We also present imaging and spectroscopy of the host galaxy obtained with the Magellan telescope. Results: The underlying afterglow appears to be a typical afterglow of a long-duration GRB. However, the material along the line of sight has imprinted very unusual features on the spectrum. First, there is a very broad and strong flux drop below 8000 Å (~4000 Å in the rest frame), which seems to be variable between the two spectroscopic epochs. We can reproduce the flux-drops both as a giant 2175 Å extinction bump and as an effect of multiple scattering on dust grains in a dense environment. Second, we detect absorption lines from excited H i and He i. We also detect molecular absorption from CH+. Conclusions: We interpret the unusual properties of these spectra as reflecting the presence of three distinct regions along the line of sight: the excited He i absorption originates from an H ii-region, whereas the Balmer absorption must originate from an associated photodissociation region. The strong metal line and molecular absorption and the dust extinction must originate from a third, cooler region along the line of sight. The presence of at least three separate regions is reflected in the fact that the different absorption components have different velocities relative to the systemic redshift of the host galaxy. Based on observations carried out under prog. ID 093.A-0069(B) with the X-shooter spectrograph installed at the Cassegrain focus of the

  13. Nitric oxide kinetics in the afterglow of a diffuse plasma filament

    NASA Astrophysics Data System (ADS)

    Burnette, D.; Montello, A.; Adamovich, I. V.; Lempert, W. R.

    2014-08-01

    A suite of laser diagnostics is used to study kinetics of vibrational energy transfer and plasma chemical reactions in a nanosecond pulse, diffuse filament electric discharge and afterglow in N2 and dry air at 100 Torr. Laser-induced fluorescence of NO and two-photon absorption laser-induced fluorescence of O and N atoms are used to measure absolute, time-resolved number densities of these species after the discharge pulse, and picosecond coherent anti-Stokes Raman spectroscopy is used to measure time-resolved rotational temperature and ground electronic state N2(v = 0-4) vibrational level populations. The plasma filament diameter, determined from plasma emission and NO planar laser-induced fluorescence images, remains nearly constant after the discharge pulse, over a few hundred microseconds, and does not exhibit expansion on microsecond time scale. Peak temperature in the discharge and the afterglow is low, T ≈ 370 K, in spite of significant vibrational nonequilibrium, with peak N2 vibrational temperature of Tv ≈ 2000 K. Significant vibrational temperature rise in the afterglow is likely caused by the downward N2-N2 vibration-vibration (V-V) energy transfer. Simple kinetic modeling of time-resolved N, O, and NO number densities in the afterglow, on the time scale longer compared to relaxation and quenching time of excited species generated in the plasma, is in good agreement with the data. In nitrogen, the N atom density after the discharge pulse is controlled by three-body recombination and radial diffusion. In air, N, NO and O concentrations are dominated by the reverse Zel'dovich reaction, N + NO → N2 + O, and ozone formation reaction, O + O2 + M → O3 + M, respectively. The effect of vibrationally excited nitrogen molecules and excited N atoms on NO formation kinetics is estimated to be negligible. The results suggest that NO formation in the nanosecond pulse discharge is dominated by reactions of excited electronic states of nitrogen, occurring on

  14. Electrical double layers at shock fronts in glow discharges and afterglows

    SciTech Connect

    Siefert, Nicholas S.

    2010-12-15

    This paper examines the propagation of spark-generated shockwaves (1.0afterglow. Diagnostic methods were employed and expanded in order to capture the dynamics of the shock front in these weakly-ionized, nonmagnetized, collisional plasmas. We used a microwave hairpin resonator to measure the electron number density, and, for all cases, we measured an increase in the electron number density at the shock front. By comparing the increase in electron number density at the shock front in the active discharge and in the afterglow, we conclude that electrons with a temperature much greater than room temperature can be compressed at the shock front. The ratio of electron number density before and after the shock front can be approximately predicted using the Rankine-Hugoniot relationship. The large gradient in electron density, and hence a large gradient in the flux of charged species, created a region of space-charge separation, i.e., a double layer, at the shock front. The double layer balances the flux of charged particles on both sides of the shock front. The double layer voltage drop was measured in the current-carrying discharge using floating probes and compared with previous models. As well, we measured argon 1s{sup 5} metastable-state density and demonstrate that metastable-state neutral species can be compressed across a shock front and approximately predicted using the Rankine-Hugoniot relationship.

  15. Effects of the offset term in experimental simulation on afterglow decay curve.

    PubMed

    Tsai, Chi-Yang; Lin, Jeng-Wen; Huang, Yih-Ping; Huang, Yung-Chieh

    2014-01-01

    This study examines the effect of the offset term in a multiple single exponential equation that fits into experimental afterglow decay curve data for material applications. For afterglow materials applied and attached to structures, the inclusion of this offset term may reduce the values of the calculated decay times, τ i , and enlarge the time invariant constants, A i , in the associated equation compared to theoretically perfect test conditions. Using a set of experimental data obtained from a lab under dim light, adjustments can be made to calculate the required parameters for an equation without the offset term. This study uses mathematical simulations and lab tests to support our thesis and crosslink test results generated from different ambient light conditions. This paper defines the offset ratio as the ratio of the offset value, I 0, versus the initial light intensity in an equation. This ratio can be used to evaluate possible effects on the calculated parameters of an equation in an associated numerical simulation. The most reliable parameters will have consistent results from the use of multiple single exponential equations, with and without the offset term, in simulations to obtain them in an equation to model a set of data.

  16. Gamma-Ray Bursts and Afterglows: a Multi-Wavelength Study in the Swift Era

    NASA Astrophysics Data System (ADS)

    Yu, Y. W.

    2010-01-01

    Gamma-ray bursts (GRBs), which are generally followed by long-lasting low-frequency afterglow emission, are short and intense pulses of gamma-rays observed from the sky in arbitrary directions. In order to observe the multi-wavelength emission at the early afterglow phase and even the prompt emission phase, NASA launched the Swift satellite on Nov. 20th 2004. Swift can localize GRBs within about 10 seconds. A brief review on the recent progress in observations and theories in the Swift era is given in Chapter 1. This paper focuses on the features of the early afterglows and the multi-wavelength prompt emission. In Chapters 2 and 3, we try to explain the shallow-decaying X-ray afterglows and X-ray flares, both of which are unaccountable in the standard afterglow model. (1) It is widely accepted that the shallow decay phase indicates a continuous energy injection into the GRB blast wave, and this energy could be released from the central engine after the burst. Based on the knowledge of the evolution of a pulsar wind, we argue that the injected flow interacting with the GRB blast wave is an ultra-relativistic kinetic-energy flow (i.e., wind) rather than pure electromagnetic waves. Therefore, a relativistic wind bubble (RWB) including a pair of shocks will be formed. Our numerical calculations and the fitting results show that the emission from an RWB can well account for the X-ray shallow decay phase. (2) For the X-ray flares that are attributed to some intermediate late activities of the central engine, we analyze the detailed dynamics of late internal shocks which directly produce the flare emission. Comparing the theoretical results with the lower limits of the observational luminosities and the profiles of the flare light curves, we find some constraints on the properties of the pre-collision shells, which are directly determined by the central object. In Chapter 4, we investigate the high-energy afterglow emission during the shallow decay phase in two models, i

  17. THE UNUSUAL RADIO AFTERGLOW OF THE ULTRA-LONG GAMMA-RAY BURST GRB 130925A

    SciTech Connect

    Horesh, Assaf; Cenko, S. Bradley; Perley, Daniel A.; Kulkarni, S. R.; Hallinan, Gregg; Bellm, Eric

    2015-10-10

    GRB 130925A is one of the recent additions to the growing family of ultra-long gamma-ray bursts (GRBs; T90 ≳1000 s). While the X-ray emission of ultra-long GRBs have been studied extensively in the past, no comprehensive radio data set has been obtained so far. We report here the early discovery of an unusual radio afterglow associated with the ultra-long GRB 130925A. The radio emission peaks at low-frequencies (∼7 GHz) at early times, only 2.2 days after the burst occurred. More notably, the radio spectrum at frequencies above 10 GHz exhibits a rather steep cut-off, compared to other long GRB radio afterglows. This cut-off can be explained if the emitting electrons are either mono-energetic or originate from a rather steep, dN/dE ∝ E{sup −4}, power-law energy distribution. An alternative electron acceleration mechanism may be required to produce such an electron energy distribution. Furthermore, the radio spectrum exhibits a secondary underlying and slowly varying component. This may hint that the radio emission we observed is comprised of emission from both a reverse and a forward shock. We discuss our results in comparison with previous works that studied the unusual X-ray spectrum of this event and discuss the implications of our findings on progenitor scenarios.

  18. AQUA: a very fast automatic reduction pipeline for near real-time GRBs early afterglow detection

    NASA Astrophysics Data System (ADS)

    Di Paola, Andrea; Antonelli, Lucio A.; Testa, Vincenzo; Patria, Giorgio

    2002-12-01

    AQUA (Automated QUick Analysis) is the fast reduction pipeline of the Near Infra-Red (NIR) images obtained by the REM telescope. REM (Rapid Eye Mount) is a robotic NIR/Optical 60cm telescope for fast detection of early afterglow of Gamma Ray Bursts (GRB). NIR observations of GRBs early afterglow are of crucial importance for GRBs science, revealing even optical obscured or high redshift events. On the technical side, they pose a series of problems: luminous background, bright sources (as the counterparts should be observed few seconds after the satellite trigger) and fast detection force high rate images acquisition. Even if the observational strategy will change during the same event observation depending on the counterpart characteristics, we will start with 1 second exposures at the fastest possible rate. The main guideline in the AQUA pipeline development is to allow such a data rate along all the night with nearly real-time results delivery. AQUA will start from the raw images and will deliver an alert with coordinates, photometry and colors to larger telescopes to allow prompt spectroscopic and polarimetric observations. Very fast processing for the raw 512×512 32bit images and variable sources detection with both sources catalogs and images comparison have been implemented to obtain a processing speed of at least 1 image/sec. AQUA is based on ANSI-C code optimized to run on a dual Athlon Linux PC with careful MMX and SSE instructions utilization.

  19. Evidence for an Early High-Energy Afterglow Observed with BATSE from GRB980923

    NASA Technical Reports Server (NTRS)

    Giblin, Tim; vanParadijs, Jan; Kouveliotou, Chryssa; Connaughton, Valerie; Wijers, Ralph A. M. J.; Fishman, Gerald

    1999-01-01

    In this letter, we present for the first time evidence in the BATSE data for a prompt high-energy (25-300 keV) afterglow component from a Gamma-Ray Burst (GRB), GRB980923. The event ranks third highest in fluence (>25 keV) in the BATSE catalog and consists of a period of rapid variability lasting about 40 s followed by a smooth power law emission tail lasting about 400 s beyond the trigger time. An abrupt change in spectral shape is found when the tail becomes noticeable. Our analysis reveals that the spectral evolution in the tail of the burst mimics that of a cooling synchrotron spectrum, similar to the spectral evolution of the low-energy afterglows for GRBS. This evidence for a separate emission component is consistent with the internal-external shock scenario in the relativistic fireball picture. In particular, it illustrates that the external shocks can be generated during the primary gamma-ray emission phase, as in the case of GRB990123.

  20. The X-shooter sample of GRB afterglow spectra: Properties of the absorption features

    NASA Astrophysics Data System (ADS)

    de Ugarte Postigo, Antonio

    2015-08-01

    Since its commissioning at ESO's Very Large Telescope in 2009, the X-shooter spectrograph has become the reference instrument in gamma-ray burst (GRB) afterglow spectroscopy. During this time our collaboration has collected more than 70 spectra of GRB afterglows, with redshifts ranging from 0.06 to 6.3. Thanks to their extreme luminosity and simple intrinsic shape, GRB spectra are optimal tools for the study of galactic environments at basically any redshift. Being produced by the death of short-lived massive stars, they are also tracers of star formation.I will present the sample of absorption spectral features identified in X-shooter's GRB spectra describing observation and analysis techniques. The different features are compared with the characteristics of the explosion (duration, spectral shape, energetics, etc.) and with the properties of the host galaxy (mass, age, etc.) to improve our understanding of the nature of the explosions and how they interact with their environments. Using the large redshift range of the spectra collection we perform studies of the evolution of GRB environments across the history of the Universe and their relation with the evolution of star formation.

  1. VizieR Online Data Catalog: GRB X-ray afterglows light curves analysis (Racusin+, 2016)

    NASA Astrophysics Data System (ADS)

    Racusin, J. L.; Oates, S. R.; de Pasquale, M.; Kocevski, D.

    2016-09-01

    All GRBs discovered with Swift-BAT, with X-ray afterglows detected by Swift-XRT and measured redshifts, between 2004 December and 2014 March are included in the analysis. We include only those X-ray afterglows with at least three light-curve bins (>~60 counts) and T90 measurements are available in the BAT catalogs (Sakamoto+ 2008, J/ApJS/175/179; 2011, J/ApJS/195/2 and Lien+ 2016, arXiv:1606.01956). The final sample includes 237 long-duration GRBs (9 short), 47 of which also appear in the Oates et al. (2012MNRAS.426L..86O; 2015MNRAS.453.4121O) sample for the UVOT correlation (sample only extends through 2010). The redshift measurements come from a convolution of databases and the literature and are listed in Table 1. All light curves were retrieved from the University of Leicester Swift XRT Team GRB repository (Evans et al. 2007A&A...469..379E; 2009, J/MNRAS/397/1177). See section 2.2 for further explanations. (2 data files).

  2. Stationary-Afterglow measurements of dissociative recombination of H2D+ and HD2+ ions

    NASA Astrophysics Data System (ADS)

    Dohnal, Petr; Kalosi, Abel; Plasil, Radek; Johnsen, Rainer; Glosik, Juraj

    2016-09-01

    Binary recombination rate coefficients of H2D+ and HD2+ ions have been measured at a temperature of 80 K in an afterglow plasma experiment in which the fractional abundances of H3+, H2D+, HD2+, and D3+ ions were varied by adjusting the [D2]/([D2] + [H2]) ratio of the neutral gas. The fractional abundances of the four ion species during the afterglow and their rotational states were determined in situ by continuous-wave cavity ring-down absorption spectroscopy (CRDS), using overtone transitions from the ground vibrational states of the ions. The experimentally determined recombination rate coefficients will be compared to results of advanced theoretical calculations and to the known H3+ and D3+ recombination rate coefficients. We conclude that the recombination coefficients depend only weakly on the isotopic composition. Astrophysical implications of the measured recombination rate coefficients will be also discussed. Work supported by: Czech Science Foundation projects GACR 14-14649P, GACR 15-15077S, GACR P209/12/0233, and by Charles University in Prague Project Nr. GAUK 692214.

  3. Spectral Energy Distributions and Light Curves of GRB 990123 and Its Afterglow

    NASA Technical Reports Server (NTRS)

    Galama, T. J.; Briggs, M. S.; Wijers,R. A. M. J.; Vreeswijk, P. M.; Rol, E.; Band, D.; vanParadijs, J.; Kouveliotou, C.; Preece, R. D.

    1999-01-01

    Gamma-ray bursts (GRBs) are thought to result from the interaction of an extremely relativistic outflow interacting with a small amount of material surrounding the site of the explosion. Multi-wavelength observations covering the gamma-ray to radio wavebands allow investigations of this "fireball" model. On 23 January 1999 optical emission was detected while the gamma-ray burst was still underway. Here we report the results of gamma-ray, optical/infra-red, sub-mm, mm and radio observations of this burst and its afterflow, which indicate that the prompt and afterflow emissions from GRB 990123 are associated with three distinct regions in the fireball. The afterglow one day after the burst has a much lower peak frequency than those of previous bursts; this explains the short-lived nature of the radio emission, which is not expected to reapear. We suggest that such differences reflect variations in the magnetic-field strengths in the afterglow emitting regions.

  4. The onset of the GeV afterglow of GRB 090510

    NASA Astrophysics Data System (ADS)

    Ghirlanda, G.; Ghisellini, G.; Nava, L.

    2010-02-01

    We study the emission of the short/hard Gamma Ray Burst 090510 at energies >0.1 GeV as observed by the Large Area Telescope (LAT) onboard the Fermi satellite. The GeV flux rises in time as t2 up till 0.2 s after the peak of the MeV pulse detected by the Fermi Gamma Burst Monitor (GBM) after which it decays as t-1.5 up to 200 s. Its energy spectrum is consistent with F(ν)∝ ν-1. The time behavior and the spectrum of the high energy LAT flux are strong evidences of an afterglow origin. We then interpret it as synchrotron radiation produced by the forward shock of a fireball with a bulk Lorentz factor Γ ˜ 2000. The afterglow peak time is independent of energy in the 0.1-30 GeV range and coincides with the arrival time of the highest energy photon (~ 30 GeV). Since the flux detected by the GBM and the LAT have different origins, the delay between these two components is not entirely due to possible violation of the Lorentz invariance. The LAT component alone allows us to set a reliable lower limit on the quantum-gravity mass of 4.7 times the Planck mass.

  5. Emission and afterglow properties of an expanding RF plasma with nonuniform neutral gas density

    NASA Astrophysics Data System (ADS)

    Chaplin, Vernon H.; Bellan, Paul M.

    2016-08-01

    We describe some notable aspects of the light emission and afterglow properties in pulsed, high-density ( 1018-1020 m-3 ) argon inductively coupled discharges initiated following fast gas injection. The plasma was created in a long, narrow discharge tube and then expanded downstream of the radiofrequency (RF) antenna into a large chamber. Fast camera images of the expanding plasma revealed a multi-phase time-dependent emission pattern that did not follow the ion density distribution. Dramatic differences in visible brightness were observed between discharges with and without an externally applied magnetic field. These phenomena were studied by tracking excited state populations using passive emission spectroscopy and are discussed in terms of the distinction between ionizing and recombining phase plasmas. Additionally, a method is presented for inferring the unknown neutral gas pressure in the discharge tube from the time-dependent visible and infrared emission measured by a simple photodiode placed near the antenna. In magnetized discharges created with fast gas injection, the downstream ion density rose by Δni˜1018 m-3 in the first ˜100 μs after the RF power was turned off. The conditions conducive to this afterglow density rise are investigated in detail, and the effect is tentatively attributed to pooling ionization.

  6. Gamma-Ray bursts: accumulating afterglow implications, progenitor clues, and prospects.

    PubMed

    Mészáros, P

    2001-01-05

    Gamma-ray bursts (GRBs) are sudden, intense flashes of gamma rays that, for a few blinding seconds, light up in an otherwise fairly dark gamma-ray sky. They are detected at the rate of about once a day, and while they are on, they outshine every other gamma-ray source in the sky, including the sun. Major advances have been made in the last 3 or 4 years, including the discovery of slowly fading x-ray, optical, and radio afterglows of GRBs, the identification of host galaxies at cosmological distances, and evidence showing that many GRBs are associated with star-forming regions and possibly supernovae. Progress has been made in understanding how the GRB and afterglow radiation arises in terms of a relativistic fireball shock model. These advances have opened new vistas and questions on the nature of the central engine, the identity of their progenitors, the effects of the environment, and their possible gravitational wave, cosmic ray, and neutrino luminosity. The debates on these issues indicate that GRBs remain among the most mysterious puzzles in astrophysics.

  7. Two-shell collisions in the gamma-ray burst afterglow phase

    NASA Astrophysics Data System (ADS)

    Vlasis, A.; van Eerten, H. J.; Meliani, Z.; Keppens, R.

    2011-07-01

    Strong optical and radio flares often appear in the afterglow phase of gamma-ray bursts (GRBs). It has been proposed that colliding ultrarelativistic shells can produce these flares. Such consecutive shells can be formed due to the variability in the central source of a GRB. We perform high-resolution 1D numerical simulations of late collisions between two ultrarelativistic shells in order to explore these events. We examine the case where a cold uniform shell collides with a self-similar Blandford & McKee shell in a constant density environment and consider cases with different Lorentz factor and energy for the uniform shell. We produce the corresponding on-axis light curves and emission images for the afterglow phase and examine the occurrence of optical and radio flares, assuming a spherical explosion and a hard-edged jet scenario. For our simulations, we use the Adaptive Mesh Refinement version of the Versatile Advection Code coupled to a linear radiative transfer code to calculate synchrotron emission. We find steeply rising flares like the behaviour of small jet opening angles and more gradual rebrightenings for large opening angles. Synchrotron self-absorption is found to strongly influence the onset and shape of the radio flare.

  8. Inactivation of Escherichia coli in the flowing afterglow of an N2 discharge at reduce pressure: study of the destruction mechanisms of bacteria and hydrodynamics of the afterglow flow

    NASA Astrophysics Data System (ADS)

    Cousty, S.; Villeger, S.; Sarette, J. P.; Ricard, A.; Sixou, M.

    2006-05-01

    We present the optimization of a sterilization process with a N{2} flowing afterglow post-discharge. First we study the inactivation of bacteria (E. coli) submitted to the post-discharge, and discuss the mechanisms of bacteria inactivation. Then we evaluate the volume repartition of the active species (N atoms produced by plasma discharge) in the chamber of treatment.

  9. Superelastic collisions under low temperature plasma and afterglow conditions: A golden rule to estimate their quantitative effects

    SciTech Connect

    D'Ammando, Giuliano Capitelli, Mario; Colonna, Gianpiero Laricchiuta, Annarita

    2015-03-15

    A simple equation describing the formation of plateaux induced by superelastic collisions in the electron energy distribution function (EEDF) of low temperature and afterglow plasmas is derived. The EEDFs predicted from this equation are in good agreement with those obtained from the numerical solution of the full Boltzmann equation in the presence of excited states.

  10. The Growth, Polarization and Motion of the Radio Afterglow from the Giant Flare from SGR 1806-20

    NASA Technical Reports Server (NTRS)

    Taylor, G. B.; Gelfand, J. D.; Gaensler, B. M.; Granot, J.; Kouveliotou, C.; Fender, R. P.; Ramirez-Ruiz, E.; Eichler, D.; Lyubarsky, Y. E.; Garrett, M.

    2005-01-01

    The extraordinary giant flare (GF) of 2004 December 27 from the soft gamma repeater (SGR) 1806-20 was followed by a bright radio afterglow. We present an analysis of VLA observations of this radio afterglow from SGR 1806-20, consisting of previously reported 8.5 GHz data covering days 7 to 20 after the GF, plus new observations at 8.5 and 22 GHz from day 24 to 81. We find a deceleration in the expansion, from approximately 4.5 mas/day to less than 2.5 mas/day. The time of deceleration is roughly coincident with the rebrightening in the radio light curve, as expected to result when the ejecta from the GF sweeps up enough of the external medium, and transitions from a coasting phase to the Sedov-Taylor regime. The radio afterglow is elongated and maintains a 2:l axis ratio with an average position angle of -40 degrees (north through east), oriented perpendicular to the average intrinsic linear polarization angle. We also report on the discovery of motion in the flux centroid of the afterglow, at an average velocity of 0.26 plus or minus 0.03 c (assuming a distance of 15 kpc) at a position angle of -40 degrees. This motion, in combination with the growth and polarization measurements, suggests an initially asymmetric outflow, mainly from one side of the magnetar.

  11. X-ray plateaus in the context of the one-zone SSC model for GRB afterglows

    SciTech Connect

    Petropoulou, M.; Mastichiadis, A.

    2010-10-15

    We investigate the impact that the upper cutoff of the electron distribution has on the multiwavelength GRB afterglow spectra and on the corresponding X-ray light curves. We show under which conditions X-ray light curves with a plateau phase can be produced in this picture.

  12. ON THE LATE-TIME SPECTRAL SOFTENING FOUND IN X-RAY AFTERGLOWS OF GAMMA-RAY BURSTS

    SciTech Connect

    Wang, Yuan-Zhu; Liang, En-Wei; Lu, Zu-Jia; Zhao, Yinan; Shao, Lang

    2016-02-20

    Strong spectral softening has been revealed in the late X-ray afterglows of some gamma-ray bursts (GRBs). The scenario of X-ray scattering around the circumburst dusty medium has been supported by previous works due to its overall successful prediction of both the temporal and spectral evolution of some X-ray afterglows. To further investigate the observed feature of spectral softening we now systematically search the X-ray afterglows detected by the X-ray telescope aboard Swift and collect 12 GRBs with significant late-time spectral softening. We find that dust scattering could be the dominant radiative mechanism for these X-ray afterglows regarding their temporal and spectral features. For some well-observed bursts with high-quality data, the time-resolved spectra could be well-produced within the scattering scenario by taking into account the X-ray absorption from the circumburst medium. We also find that during spectral softening the power-law index in the high-energy end of the spectra does not vary much. The spectral softening is mainly manifested by the spectral peak energy continually moving to the soft end.

  13. I-V characteristics of the Langmuir probe in flowing afterglow plasmas

    NASA Astrophysics Data System (ADS)

    Shun'ko, E. V.

    2003-04-01

    The specific features of the probe I-V characteristics in flowing-afterglow plasmas are studied experimentally and in theory. As it was found at a probe potential equal to the plasma one, V=0, an electron concentration in a probe vicinity (and a probe current) is decreased due to a predominant outflow of the electrons into an electrical circuit of the probe from the probe vicinity. The expression allowing one to reconstruct the undisturbed-by-probe electron concentration from only experimental data is derived. The reconstructed values of the electron concentration enable one to find from the experiments the semiempiric expressions allowing to describe quantitatively the behavior of the probe I-V characteristics at the electron-attracting as well as at the ion-attracting potential, respectively. The expressions found (both for electron-attracting and ion-attracting potential) include the "separating length," which merely is the Langmuir length with a factor equal to the square root of the electron mass over the ion mass ratio for two-component plasma. The intermediate part of the probe I-V characteristics is discovered for probes operating with afterglow plasmas. This intermediate part is described in terms of the experimental parameter L0 having a dimension of the length (presumably electron-orbital length). The value of the parameter L0 does not depend on plasma parameters to within the ranges of plasma parameter variations for experimentally investigated plasmas as it was found. The experiments were performed with two cylindrical probes of 10 and 25 μm diam and ˜3 mm lengths in the experimentally investigated ranges of the afterglow plasma parameters: 105 cm-3

  14. GRB 070125 and the environments of spectral-line poor afterglow absorbers

    NASA Astrophysics Data System (ADS)

    De Cia, A.; Starling, R. L. C.; Wiersema, K.; van der Horst, A. J.; Vreeswijk, P. M.; Björnsson, G.; de Ugarte Postigo, A.; Jakobsson, P.; Levan, A. J.; Rol, E.; Schulze, S.; Tanvir, N. R.

    2011-11-01

    GRB 070125 is among the most energetic bursts detected and the most extensively observed so far. Nevertheless, unresolved issues are still open in the literature on the physics of the afterglow and on the gamma-ray burst (GRB) environment. In particular, GRB 070125 was claimed to have exploded in a galactic halo environment, based on the uniqueness of the optical spectrum and the non-detection of an underlying host galaxy. In this work we collect all publicly available data and address these issues by modelling the near-infrared to X-ray spectral energy distribution (SED) and studying the high signal-to-noise ratio Very Large Telescope/FOcal Reducer/low dispersion Spectrograph afterglow spectrum in comparison with a larger sample of GRB absorbers. The SED reveals a synchrotron cooling break in the ultraviolet, low equivalent hydrogen column density and little reddening caused by a Large Magellanic Cloud type or Small Magellanic Cloud type extinction curve. From the weak Mg II absorption at z= 1.5477 in the spectrum, we derived log N(Mg II) = 12.96+0.13- 0.18 and upper limits on the ionic column density of several metals. These suggest that the GRB absorber is most likely a Lyman limit system with a 0.03 < Z < 1.3 Z⊙ metallicity. The comparison with other GRB absorbers places GRB 070125 at the low end of the absorption-line equivalent width distribution, confirming that weak spectral features and spectral-line poor absorbers are not so uncommon in afterglow spectra. Moreover, we show that the effect of photoionization on the gas surrounding the GRB, combined with a low N(H I) along a short segment of the line of sight within the host galaxy, can explain the lack of spectral features in GRB 070125. Finally, the non-detection of an underlying galaxy is consistent with a faint GRB host galaxy, well within the GRB host brightness distribution. Thus, the possibility that GRB 070125 is simply located in the outskirts of a gas-rich, massive star-forming region inside its

  15. Plastic Damping of Alfvén Waves in Magnetar Flares and Delayed Afterglow Emission

    NASA Astrophysics Data System (ADS)

    Li, Xinyu; Beloborodov, Andrei M.

    2015-12-01

    Magnetar flares generate Alfvén waves bouncing in the closed magnetosphere with energy up to ∼ {10}46 erg. We show that on a timescale of 10 ms the waves are transmitted into the star and form a compressed packet of high energy density. This packet strongly shears the stellar crust and initiates a plastic flow, heating the crust and melting it hundreds of meters below the surface. A fraction of the deposited plastic heat is eventually conducted to the stellar surface, contributing to the surface afterglow months to years after the flare. A large fraction of heat is lost to neutrino emission or conducted into the core of the neutron star.

  16. Electron-Ion Recombination Rate Coefficient Measurements in a Flowing Afterglow Plasma

    NASA Technical Reports Server (NTRS)

    Gougousi, Theodosia; Golde, Michael F.; Johnsen, Rainer

    1996-01-01

    The flowing-afterglow technique in conjunction with computer modeling of the flowing plasma has been used to determine accurate dissociative-recombination rate coefficients alpha for the ions O2(+), HCO(+), CH5(+), C2H5(+), H3O(+), CO2(+), HCO2(+), HN2O(+), and N2O(+) at 295 K. We find that the simple form of data analysis that was employed in earlier experiments was adequate and we largely confirm earlier results. In the case of HCO(+) ions, published coefficients range from 1.1 X 10(exp -7) to 2.8 x 10(exp -7) cu cm/S, while our measurements give a value of 1.9 x 10(exp -7) cu cm/S.

  17. Production of and Dissociative Electron Attachment to the Simplest Criegee Intermediate in an Afterglow.

    PubMed

    Wiens, Justin P; Shuman, Nicholas S; Viggiano, Albert A

    2015-02-05

    The simplest Criegee intermediate, CH2OO, has been produced in a flowing afterglow using a novel technique. CH2I is produced by dissociative electron attachment to CH2I2, leading to the established reaction CH2I + O2 → CH2OO + I. The presence of CH2OO is established by observation of dissociative electron attachment to yield O(-) using the variable electron and neutral density attachment mass spectrometry (VENDAMS) technique. The measurements establish the electron attachment rate coefficient of thermal electrons at 300 K to CH2OO as 1.2 ± 0.3 × 10(-8) cm(3) s(-1). Thermal electron attachment is solely dissociative and is not a promising route to producing stable CH2OO(-). The results open the possibility of measuring ion-molecule chemistry involving Criegee intermediates, as well as the reactivity of other unstable radicals produced in an analogous manner.

  18. Wide field x-ray telescopes: Detecting x-ray transients/afterglows related to GRBs

    SciTech Connect

    Hudec, Rene; Pina, Ladislav; Inneman, Adolf; Gorenstein, Paul

    1998-05-16

    The recent discovery of X-ray afterglows of GRBs opens the possibility of analyses of GRBs by their X-ray detections. However, imaging X-ray telescopes in current use mostly have limited fields of view. Alternative X-ray optics geometries achieving very large fields of view have been theoretically suggested in the 70's but not constructed and used so far. We review the geometries and basic properties of the wide-field X-ray optical systems based on one- and two-dimensional lobster-eye geometry and suggest technologies for their development and construction. First results of the development of double replicated X-ray reflecting flats for use in one-dimensional X-ray optics of lobster-eye type are presented and discussed. The optimum strategy for locating GRBs upon their X-ray counterparts is also presented and discussed.

  19. VERY HIGH ENERGY gamma-RAY AFTERGLOW EMISSION OF NEARBY GAMMA-RAY BURSTS

    SciTech Connect

    Xue, R. R.; Fan, Y. Z.; Wei, D. M.; Tam, P. H.; Wagner, S. J.; Behera, B. E-mail: phtam@lsw.uni-heidelberg.d

    2009-09-20

    The synchrotron self-Compton (SSC) emission from gamma-ray burst (GRB) forward shock can extend to the very high energy (VHE; E{sub {gamma}} > 100 GeV) range. Such high energy photons are rare and are attenuated by the cosmic infrared background before reaching us. In this work, we discuss the prospect to detect these VHE photons using the current ground-based Cherenkov detectors. Our calculated results are consistent with the upper limits obtained with several Cherenkov detectors for GRB 030329, GRB 050509B, and GRB 060505 during the afterglow phase. For five bursts in our nearby GRB sample (except for GRB 030329), current ground-based Cherenkov detectors would not be expected to detect the modeled VHE signal. Only for those very bright and nearby bursts like GRB 030329, detection of VHE photons is possible under favorable observing conditions and a delayed observation time of {approx}<10 hr.

  20. A possible macronova in the late afterglow of the long-short burst GRB 060614.

    PubMed

    Yang, Bin; Jin, Zhi-Ping; Li, Xiang; Covino, Stefano; Zheng, Xian-Zhong; Hotokezaka, Kenta; Fan, Yi-Zhong; Piran, Tsvi; Wei, Da-Ming

    2015-06-11

    Long-duration (>2 s) γ-ray bursts that are believed to originate from the death of massive stars are expected to be accompanied by supernovae. GRB 060614, that lasted 102 s, lacks a supernova-like emission down to very stringent limits and its physical origin is still debated. Here we report the discovery of near-infrared bump that is significantly above the regular decaying afterglow. This red bump is inconsistent with even the weakest known supernova. However, it can arise from a Li-Paczyński macronova--the radioactive decay of debris following a compact binary merger. If this interpretation is correct, GRB 060614 arose from a compact binary merger rather than from the death of a massive star and it was a site of a significant production of heavy r-process elements. The significant ejected mass favours a black hole-neutron star merger but a double neutron star merger cannot be ruled out.

  1. Collisional-Radiative Recombination of Ar^+ Ions with Electrons in a Flowing Afterglow Plasma.

    NASA Astrophysics Data System (ADS)

    Skrzypkowski, Miroslaw P.; Golde, Michael F.; Johnsen, Rainer

    1998-10-01

    Langmuir probe measurements of electron densities, n_e, in an Ar^+/e^- plasma are quantitatively consistent with the semi-empirical rate coefficient for collisional-radiative recombination given by Stevefelt et al.(J. Stevefelt et al., Phys. Rev A 12, 1246 (1975)) : α_cr=1.55×10-10T-0.63 + 6.0×10-9T-2.18n_e^0.37+3.8×10- 9T-4.5ne over the initial electron density range 5×10^9-5×10^10cm-3 at T=300K. Optical emission spectroscopy data reveal transitions from highly-excited states of Ar to Ar(^3P). We believe that the collisional-radiative recombination of Ar^+ ions is responsible for the presence of Ar metastable atoms in flowing afterglow plasmas.

  2. THE AFTERGLOW AND ULIRG HOST GALAXY OF THE DARK SHORT GRB 120804A

    SciTech Connect

    Berger, E.; Zauderer, B. A.; Margutti, R.; Laskar, T.; Fong, W.; Chornock, R.; Dupuy, T. J.; Levan, A.; Tunnicliffe, R. L.; Mangano, V.; Fox, D. B.; Tanvir, N. R.; Menten, K. M.; Hjorth, J.; Roth, K.

    2013-03-10

    We present the optical discovery and subarcsecond optical and X-ray localization of the afterglow of the short GRB 120804A, as well as optical, near-IR, and radio detections of its host galaxy. X-ray observations with Swift/XRT, Chandra, and XMM-Newton extending to {delta}t Almost-Equal-To 19 days reveal a single power-law decline. The optical afterglow is faint, and comparison to the X-ray flux indicates that GRB 120804A is ''dark'', with a rest-frame extinction of A {sup host}{sub V} Almost-Equal-To 2.5 mag (at z = 1.3). The intrinsic neutral hydrogen column density inferred from the X-ray spectrum, N{sub H,{sub int}}(z = 1.3) Almost-Equal-To 2 Multiplication-Sign 10{sup 22} cm{sup -2}, is commensurate with the large extinction. The host galaxy exhibits red optical/near-IR colors. Equally important, JVLA observations at Almost-Equal-To 0.9-11 days reveal a constant flux density of F{sub {nu}}(5.8 GHz) = 35 {+-} 4 {mu}Jy and an optically thin spectrum, unprecedented for GRB afterglows, but suggestive instead of emission from the host galaxy. The optical/near-IR and radio fluxes are well fit with the scaled spectral energy distribution of the local ultraluminous infrared galaxy (ULIRG) Arp 220 at z Almost-Equal-To 1.3, with a resulting star formation rate of x Almost-Equal-To 300 M{sub Sun} yr{sup -1}. The inferred extinction and small projected offset (2.2 {+-} 1.2 kpc) are also consistent with the ULIRG scenario, as is the presence of a companion galaxy at the same redshift and with a separation of about 11 kpc. The limits on radio afterglow emission, in conjunction with the observed X-ray and optical emission, require a circumburst density of n {approx} 10{sup -3} cm{sup -3}, an isotropic-equivalent energy scale of E{sub {gamma},{sub iso}} Almost-Equal-To E{sub K,{sub iso}} Almost-Equal-To 7 Multiplication-Sign 10{sup 51} erg, and a jet opening angle of {theta}{sub j} {approx}> 11 Degree-Sign . The expected fraction of luminous infrared galaxies in the short GRB

  3. Effective absorbing column density in the gamma-ray burst afterglow X-ray spectra

    NASA Astrophysics Data System (ADS)

    Campana, S.; Bernardini, M. G.; Braito, V.; Cusumano, G.; D'Avanzo, P.; D'Elia, V.; Ghirlanda, G.; Ghisellini, G.; Melandri, A.; Salvaterra, R.; Tagliaferri, G.; Vergani, S. D.

    2014-07-01

    We investigate the scaling relation between the observed amount of absorption in the X-ray spectra of gamma-ray burst afterglows and the absorber redshift. Through dedicated numerical simulations of an ideal instrument, we establish that this dependence has a power-law shape with index 2.4. However, for real instruments, this value depends on their low-energy cut-off, spectral resolution and on the detector spectral response in general. We thus provide appropriate scaling laws for specific instruments. Finally, we discuss the possibility to measure the absorber redshift from X-ray data alone. We find that 105-106 counts in the 0.3-10 keV band are needed to constrain the redshift with 10 per cent accuracy. As a test case, we discuss the XMM-Newton observation of GRB 090618 at z = 0.54. We are able to recover the correct redshift of this burst with the expected accuracy.

  4. The rapid decay phase of the afterglow as the signature of the Blandford-Znajek mechanism

    NASA Astrophysics Data System (ADS)

    Nathanail, A.; Strantzalis, A.; Contopoulos, I.

    2016-02-01

    Gamma-ray bursts (GRBs) are believed to be powered by the electromagnetic extraction of spin energy from a black hole endowed with a magnetic field supported by electric currents in a surrounding disc (Blandford & Znajek). A generic feature of this mechanism is that, under certain fairly general assumptions, the energy loss rate decays exponentially. In this work, we are looking precisely for such exponential decay in the light curves of long-duration GRBs observed with the X-ray telescope (XRT) instrument on the Swift satellite. We found out that almost 30 per cent of XRT light curves show such behaviour before they reach the afterglow plateau. According to Blandford & Znajek, the duration of the burst depends on the magnetic flux accumulated on the event horizon. This allows us to estimate the surface magnetic field of a possible progenitor. Our estimations are consistent with magnetic fields observed in Wolf-Rayet stars.

  5. The Giant Flare From SGR 1806-20 And Its Radio Afterglow

    SciTech Connect

    Taylor, G.B.; Granot, J.; /KIPAC, Menlo Park

    2006-09-26

    The multi-wavelength observations of the 2004 December 27 Giant Flare (GF) from SGR 1806-20 and its long-lived radio afterglow are briefly reviewed. The GF appears to have been produced by a dramatic reconfiguration of the magnetic field near the surface of the neutron star, possibly accompanied by fractures in the crust. The explosive release of over 10{sup 46} erg (isotropic equivalent) powered a one-sided mildly relativistic outflow. The outflow produced a new expanding radio nebula, that is still visible over a year after the GF. Also considered are the constraints on the total energy in the GF, the energy and mass in the outflow, and on the external density, as well as possible implications for short {gamma}-ray bursts and potential signatures in high energy neutrinos, photons, or cosmic rays. Some possible future observations of this and other GFs are briefly discussed.

  6. A possible macronova in the late afterglow of the long-short burst GRB 060614

    NASA Astrophysics Data System (ADS)

    Yang, Bin; Jin, Zhi-Ping; Li, Xiang; Covino, Stefano; Zheng, Xian-Zhong; Hotokezaka, Kenta; Fan, Yi-Zhong; Piran, Tsvi; Wei, Da-Ming

    2015-06-01

    Long-duration (>2 s) γ-ray bursts that are believed to originate from the death of massive stars are expected to be accompanied by supernovae. GRB 060614, that lasted 102 s, lacks a supernova-like emission down to very stringent limits and its physical origin is still debated. Here we report the discovery of near-infrared bump that is significantly above the regular decaying afterglow. This red bump is inconsistent with even the weakest known supernova. However, it can arise from a Li-Paczyński macronova--the radioactive decay of debris following a compact binary merger. If this interpretation is correct, GRB 060614 arose from a compact binary merger rather than from the death of a massive star and it was a site of a significant production of heavy r-process elements. The significant ejected mass favours a black hole-neutron star merger but a double neutron star merger cannot be ruled out.

  7. A Large Catalog of Homogeneous Ultra-Violet/Optical GRB Afterglows: Temporal and Spectral Evolution

    NASA Astrophysics Data System (ADS)

    Roming, Peter W. A.; Koch, T. Scott; Oates, Samantha R.; Porterfield, Blair L.; Bayless, Amanda J.; Breeveld, Alice A.; Gronwall, Caryl; Kuin, N. P. M.; Page, Mat J.; de Pasquale, Massimiliano; Siegel, Michael H.; Swenson, Craig A.; Tobler, Jennifer M.

    2017-02-01

    We present the second Swift Ultra-Violet/Optical Telescope (UVOT) gamma-ray burst (GRB) afterglow catalog, greatly expanding on the first Swift UVOT GRB afterglow catalog. The second catalog is constructed from a database containing over 120,000 independent UVOT observations of 538 GRBs first detected by Swift, the High Energy Transient Explorer 2 (HETE2), the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), the Interplanetary Network (IPN), Fermi, and Astro-rivelatore Gamma a Immagini Leggero (AGILE). The catalog covers GRBs discovered from 2005 January 17 to 2010 December 25. Using photometric information in three UV bands, three optical bands, and a “white” or open filter, the data are optimally coadded to maximize the number of detections and normalized to one band to provide a detailed light curve. The catalog provides positional, temporal, and photometric information for each burst, as well as Swift Burst Alert Telescope and X-ray Telescope (XRT) GRB parameters. Temporal slopes are provided for each UVOT filter. The temporal slope per filter of almost half the GRBs are fit with a single power law, but one to three breaks are required in the remaining bursts. Morphological comparisons with the X-ray reveal that ∼ 75 % of the UVOT light curves are similar to one of the four morphologies identified by Evans et al. (2009). The remaining ∼ 25 % have a newly identified morphology. For many bursts, redshift- and extinction-corrected UV/optical spectral slopes are also provided at 2 × 103, 2 × 104, and 2 × 105 s.

  8. Gamma-ray Burst Reverse Shock Emission in Early Radio Afterglows

    NASA Astrophysics Data System (ADS)

    Resmi, Lekshmi; Zhang, Bing

    2016-07-01

    Reverse shock (RS) emission from gamma-ray bursts is an important tool in investigating the nature of the ejecta from the central engine. If the magnetization of the ejecta is not high enough to suppress the RS, a strong RS emission component, usually peaking in the optical/IR band early on, would provide an important contribution to early afterglow light curve. In the radio band, synchrotron self-absorption may suppress early RS emission and also delay the RS peak time. In this paper, we calculate the self-absorbed RS emission in the radio band under different dynamical conditions. In particular, we stress that the RS radio emission is subject to self-absorption in both RSs and forward shocks (FSs). We calculate the ratio between the RS to FS flux at the RS peak time for different frequencies, which is a measure of the detectability of the RS emission component. We then constrain the range of physical parameters for a detectable RS, in particular the role of magnetization. We notice that unlike optical RS emission which is enhanced by moderate magnetization, moderately magnetized ejecta do not necessarily produce a brighter radio RS due to the self-absorption effect. For typical parameters, the RS emission component would not be detectable below 1 GHz unless the medium density is very low (e.g., n < 10-3 cm-3 for the interstellar medium and A * < 5 × 10-4 for wind). These predictions can be tested using the afterglow observations from current and upcoming radio facilities such as the Karl G. Jansky Very Large Array, the Low-Frequency Array, the Five Hundred Meter Aperture Spherical Telescope, and the Square Kilometer Array.

  9. PANCHROMATIC OBSERVATIONS OF THE TEXTBOOK GRB 110205A: CONSTRAINING PHYSICAL MECHANISMS OF PROMPT EMISSION AND AFTERGLOW

    SciTech Connect

    Zheng, W.; Shen, R. F.; Sakamoto, T.; Beardmore, A. P.; De Pasquale, M.; Wu, X. F.; Zhang, B.; Gorosabel, J.; Urata, Y.; Sugita, S.; Pozanenko, A.; Sahu, D. K.; Im, M.; Ukwatta, T. N.; Andreev, M.; Klunko, E. E-mail: rfshen@astro.utoronto.ca; and others

    2012-06-01

    We present a comprehensive analysis of a bright, long-duration (T{sub 90} {approx} 257 s) GRB 110205A at redshift z = 2.22. The optical prompt emission was detected by Swift/UVOT, ROTSE-IIIb, and BOOTES telescopes when the gamma-ray burst (GRB) was still radiating in the {gamma}-ray band, with optical light curve showing correlation with {gamma}-ray data. Nearly 200 s of observations were obtained simultaneously from optical, X-ray, to {gamma}-ray (1 eV to 5 MeV), which makes it one of the exceptional cases to study the broadband spectral energy distribution during the prompt emission phase. In particular, we clearly identify, for the first time, an interesting two-break energy spectrum, roughly consistent with the standard synchrotron emission model in the fast cooling regime. Shortly after prompt emission ({approx}1100 s), a bright (R = 14.0) optical emission hump with very steep rise ({alpha} {approx} 5.5) was observed, which we interpret as the reverse shock (RS) emission. It is the first time that the rising phase of an RS component has been closely observed. The full optical and X-ray afterglow light curves can be interpreted within the standard reverse shock (RS) + forward shock (FS) model. In general, the high-quality prompt and afterglow data allow us to apply the standard fireball model to extract valuable information, including the radiation mechanism (synchrotron), radius of prompt emission (R{sub GRB} {approx} 3 Multiplication-Sign 10{sup 13} cm), initial Lorentz factor of the outflow ({Gamma}{sub 0} {approx} 250), the composition of the ejecta (mildly magnetized), the collimation angle, and the total energy budget.

  10. GAMMA-RAY BURST DYNAMICS AND AFTERGLOW RADIATION FROM ADAPTIVE MESH REFINEMENT, SPECIAL RELATIVISTIC HYDRODYNAMIC SIMULATIONS

    SciTech Connect

    De Colle, Fabio; Ramirez-Ruiz, Enrico; Granot, Jonathan; Lopez-Camara, Diego

    2012-02-20

    We report on the development of Mezcal-SRHD, a new adaptive mesh refinement, special relativistic hydrodynamics (SRHD) code, developed with the aim of studying the highly relativistic flows in gamma-ray burst sources. The SRHD equations are solved using finite-volume conservative solvers, with second-order interpolation in space and time. The correct implementation of the algorithms is verified by one-dimensional (1D) and multi-dimensional tests. The code is then applied to study the propagation of 1D spherical impulsive blast waves expanding in a stratified medium with {rho}{proportional_to}r{sup -k}, bridging between the relativistic and Newtonian phases (which are described by the Blandford-McKee and Sedov-Taylor self-similar solutions, respectively), as well as to a two-dimensional (2D) cylindrically symmetric impulsive jet propagating in a constant density medium. It is shown that the deceleration to nonrelativistic speeds in one dimension occurs on scales significantly larger than the Sedov length. This transition is further delayed with respect to the Sedov length as the degree of stratification of the ambient medium is increased. This result, together with the scaling of position, Lorentz factor, and the shock velocity as a function of time and shock radius, is explained here using a simple analytical model based on energy conservation. The method used for calculating the afterglow radiation by post-processing the results of the simulations is described in detail. The light curves computed using the results of 1D numerical simulations during the relativistic stage correctly reproduce those calculated assuming the self-similar Blandford-McKee solution for the evolution of the flow. The jet dynamics from our 2D simulations and the resulting afterglow light curves, including the jet break, are in good agreement with those presented in previous works. Finally, we show how the details of the dynamics critically depend on properly resolving the structure of the

  11. Gamma-Ray Burst Dynamics and Afterglow Radiation from Adaptive Mesh Refinement, Special Relativistic Hydrodynamic Simulations

    NASA Astrophysics Data System (ADS)

    De Colle, Fabio; Granot, Jonathan; López-Cámara, Diego; Ramirez-Ruiz, Enrico

    2012-02-01

    We report on the development of Mezcal-SRHD, a new adaptive mesh refinement, special relativistic hydrodynamics (SRHD) code, developed with the aim of studying the highly relativistic flows in gamma-ray burst sources. The SRHD equations are solved using finite-volume conservative solvers, with second-order interpolation in space and time. The correct implementation of the algorithms is verified by one-dimensional (1D) and multi-dimensional tests. The code is then applied to study the propagation of 1D spherical impulsive blast waves expanding in a stratified medium with ρvpropr -k , bridging between the relativistic and Newtonian phases (which are described by the Blandford-McKee and Sedov-Taylor self-similar solutions, respectively), as well as to a two-dimensional (2D) cylindrically symmetric impulsive jet propagating in a constant density medium. It is shown that the deceleration to nonrelativistic speeds in one dimension occurs on scales significantly larger than the Sedov length. This transition is further delayed with respect to the Sedov length as the degree of stratification of the ambient medium is increased. This result, together with the scaling of position, Lorentz factor, and the shock velocity as a function of time and shock radius, is explained here using a simple analytical model based on energy conservation. The method used for calculating the afterglow radiation by post-processing the results of the simulations is described in detail. The light curves computed using the results of 1D numerical simulations during the relativistic stage correctly reproduce those calculated assuming the self-similar Blandford-McKee solution for the evolution of the flow. The jet dynamics from our 2D simulations and the resulting afterglow light curves, including the jet break, are in good agreement with those presented in previous works. Finally, we show how the details of the dynamics critically depend on properly resolving the structure of the relativistic flow.

  12. Afterglow rebrightenings as a signature of a long-lasting central engine activity?. The emblematic case of GRB 100814A

    NASA Astrophysics Data System (ADS)

    Nardini, M.; Elliott, J.; Filgas, R.; Schady, P.; Greiner, J.; Krühler, T.; Klose, S.; Afonso, P.; Kann, D. A.; Nicuesa Guelbenzu, A.; Olivares E., F.; Rau, A.; Rossi, A.; Sudilovsky, V.; Schmidl, S.

    2014-02-01

    Context. In the past few years the number of well-sampled optical to near-infrared (NIR) light curves of long gamma-ray bursts (GRBs) has greatly increased, particularly due to simultaneous multi-band imagers such as GROND. Combining these densely sampled ground-based data sets with the Swift UVOT and XRT space observations unveils a much more complex afterglow evolution than what was predicted by the most commonly invoked theoretical models. GRB 100814A represents a remarkable example of these interesting well-sampled events, showing a prominent late-time rebrightening in the optical to NIR bands and a complex spectral evolution. This represents a unique laboratory to test the different afterglow emission models. Aims: Here we study the nature of the complex afterglow emission of GRB 100814A in the framework of different theoretical models. Moreover, we compare the late-time chromatic rebrightening with those observed in other well-sampled long GRBs. Methods: We analysed the optical and NIR observations obtained with the seven-channel Gamma-Ray burst Optical and Near-infrared Detector (GROND) at the 2.2 m MPG/ESO telescope together with the X-ray and UV data detected by the instruments onboard the Swift observatory. The broad-band afterglow evolution, achieved by constructing multi-instrument light curves and spectral energy distributions, is discussed in the framework of different theoretical models. Results: We find that the standard models that describe the broad-band afterglow emission within the external shock scenario fail to describe the complex evolution of GRB 100814A, and therefore more complex scenarios must be invoked. The analysis of the very well sampled broad-band light curve of GRB 100814A allowed us to deduce that models invoking late-time activity of the central engine in the observed afterglow emission are the preferred ones for all the different observed features. This late-time activity most likely has the form of a delayed reactivation of the

  13. Probing a GRB Progenitor at a Redshift of z=2: A Comprehensive Observing Campaign of the Afterglow of GRB 030226l

    NASA Technical Reports Server (NTRS)

    Klose, S.; Greiner, J.; Rau, A.; Henden, A. A.; Hartmann, D. H.; Zeh, A.; Ries, C.; Masetti, N.; Malesani, D.; Guenther, E.

    2004-01-01

    We report results from a comprehensive optical/near-infrared follow-up observing campaign of the afterglow of GRB 030226, including VLT spectroscopy and polarimetry, supplemented by Chandra X-ray and BOOTES-1 rapid response observations. First observations at ESO started 0.2 days after the burst when the afterglow was at a magnitude of R approx. 19. The multi-color light curve of the afterglow, with a break around 1 day after the burst, is achromatic within the observational uncertainties even during episodes of short-term fluctuations. Close to the break time the degree of linear polarization of the afterglow light was less than 1.1%, consistent with low intrinsic polarization observed in other afterglows. VLT spectra show a foreground absorber of Mg II at a redshift z=1.042 and two absorption line systems at redshifts z=1.962+/-0.001 and at z=1.986+/-0.001, placing the lower limit for the redshift of the GRB close to 2. The kinematics and the composition of the absorbing clouds is very similar to those observed in the afterglow of GRB 021004, supporting the view that at least some GRBs are physically related to the explosion of a Wolf-Rayet star.

  14. Use of Interrupted Helium Flow in the Analysis of Vapor Samples with Flowing Atmospheric-Pressure Afterglow-Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Storey, Andrew P.; Zeiri, Offer M.; Ray, Steven J.; Hieftje, Gary M.

    2017-02-01

    The flowing atmospheric-pressure afterglow (FAPA) source was used for the mass-spectrometric analysis of vapor samples introduced between the source and mass spectrometer inlet. Through interrupted operation of the plasma-supporting helium flow, helium consumption is greatly reduced and dynamic gas behavior occurs that was characterized by schlieren imaging. Moreover, mass spectra acquired immediately after the onset of helium flow exhibit a signal spike before declining and ultimately reaching a steady level. This initial signal appears to be due to greater interaction of sample vapor with the afterglow of the source when helium flow resumes. In part, the initial spike in signal can be attributed to a pooling of analyte vapor in the absence of helium flow from the source. Time-resolved schlieren imaging of the helium flow during on and off cycles provided insight into gas-flow patterns between the FAPA source and the MS inlet that were correlated with mass-spectral data.

  15. Two Early Gamma-ray Bursts Optical Afterglow Detections with TAOS Telescopes--GRB 071010B and GRB 071112C

    SciTech Connect

    Huang, K. Y.; Wang, S. Y.; Urata, Y.

    2009-05-25

    We present on two early detections of GRB afterglows with the Taiwanese-American Occltation Sruvey (TAOS) telescopes. The robotic TAOS system has been devised so that the routine Kuiper Belt Object (KBO) survey is interrupted when a GRB alert is triggered. Our first detection, GRB 071010B was detected by TAOS 62 s after the burst and showed a weak early brightening during the observations. No significant correction with the prompt gamma-ray emission indicated that our optical emission detected is afterglow emission. The second detection of TAOS, GRB 071112C was detected 96 s after the burst, also showed a possible initial raising then followed a steep decay in the R-band light curve.

  16. Lifetime and quenching of CO /a super 3 pi/ produced by recombination of CO2 ions in a helium afterglow.

    NASA Technical Reports Server (NTRS)

    Wauchop, T. S.; Broida, H. P.

    1972-01-01

    Demonstration that rapid dissociative recombination of CO2(+) in a flowing, helium afterglow is an efficient source of CO in the a super 3 pi metastable state. Ions produced by mixing CO2 with He(2 super 3 S) recombine to produce a CO metastable afterglow with a number density as great as 10 to the 9th per sq cm. Monitoring of the (a super 3 pi-X super 1 sigma) Cameron transition in CO was used to study the lifetime and quenching of CO (a super 3 pi) by CO2, N2, NO, and He. Recombination of CO2(+) also produces CO in the d super 3 delta and a' super 3 sigma states.

  17. The Production and Evolution of Atomic Oxygen in the Afterglow of Streamer Discharge in Atmospheric Pressure Fuel/Air Mixtures

    DTIC Science & Technology

    2013-07-02

    in streamer discharge afterglow in a variety of fueVair mixtures in order to account for the 0 reaction pathways in transient plasma ignition. It is... plasma ignition (TPI), the use of streamers for ignition in combustion engines, holds great promise for improving performance. TPI has been tested...standard spark gap or arc ignition methods [1-4]. These improvements to combustion allow increasing power and efficiency in existing engines such as

  18. THERMAL EMISSIONS SPANNING THE PROMPT AND THE AFTERGLOW PHASES OF THE ULTRA-LONG GRB 130925A

    SciTech Connect

    Basak, Rupal; Rao, A. R. E-mail: arrao@tifr.res.in

    2015-07-01

    GRB 130925A is an ultra-long gamma-ray burst (GRB), and it shows clear evidence for thermal emission in the soft X-ray data of the Swift/X-ray Telescope (XRT; ∼0.5 keV), lasting until the X-ray afterglow phase. Due to the long duration of the GRB, the burst could be studied in hard X-rays with high-resolution focusing detectors (NuSTAR). The blackbody temperature, as measured by the Swift/XRT, shows a decreasing trend until the late phase (Piro et al.) whereas the high-energy data reveal a significant blackbody component during the late epochs at an order of magnitude higher temperature (∼5 keV) compared to contemporaneous low energy data (Bellm et al.). We resolve this apparent contradiction by demonstrating that a model with two black bodies and a power law (2BBPL) is consistent with the data right from the late prompt emission to the afterglow phase. Both blackbodies show a similar cooling behavior up to late times. We invoke a structured jet, having a fast spine and a slower sheath layer, to identify the location of these blackbodies. Independent of the physical interpretation, we propose that the 2BBPL model is a generic feature of the prompt emission of all long GRBs, and the thermal emission found in the afterglow phase of different GRBs reflects the lingering thermal component of the prompt emission with different timescales. We strengthen this proposal by pointing out a close similarity between the spectral evolutions of this GRB and GRB 090618, a source with significant wide band data during the early afterglow phase.

  19. Soft X-ray emission lines in the afterglow spectrum of GRB 011211: A detailed XMM-Newton analysis

    NASA Astrophysics Data System (ADS)

    Reeves, J. N.; Watson, D.; Osborne, J. P.; Pounds, K. A.; O'Brien, P. T.

    2003-05-01

    We report on an XMM-Newton observation of the X-ray afterglow of the Gamma Ray Burst GRB 011211, originally detected by Beppo-SAX on 11th December 2001. The early afterglow spectrum obtained by XMM-Newton, observed 11 hours after the initial burst, appeared to reveal decaying H-like Kalpha emission lines of Mg, Si, S, Ar and Ca, arising in enriched material with an outflow velocity of order 0.1c (Reeves et al. \\cite{Reeves2002}). This was attributed to matter ejected from a massive stellar progenitor occurring shortly before the burst itself. Here, we present a detailed re-analysis of the XMM-Newton EPIC observations of GRB 011211. In particular, we show that the detection of the soft X-ray line emission appears robust, regardless of detector background, calibration, spectral binning, or the spectral model that is assumed. We demonstrate that thermal emission, from an optically thin plasma, is the most plausible model that can account for the soft X-ray emission, which appears to be the case for at least two burst afterglow spectra observed by XMM-Newton. The X-ray spectrum of GRB 011211 appears to evolve with time after the first 10 ks of the XMM-Newton observation as the Si and S emission lines are only detected during the first 10 ks of observation. The observations suggest that thermal emission is present during the early afterglow spectrum, whilst a power-law component dominates the latter stages. Finally we estimate the mass of the ejected material in GRB 011211 to be of the order 4-20 solar masses.

  20. Implications from the Upper Limit of Radio Afterglow Emission of FRB 131104/Swift J0644.5-5111

    NASA Astrophysics Data System (ADS)

    Gao, He; Zhang, Bing

    2017-02-01

    A γ-ray transient, Swift J0644.5-5111, has been claimed to be associated with FRB 131104. However, a long-term radio imaging follow-up observation only placed an upper limit on the radio afterglow flux of Swift J0644.5-5111. Applying the external shock model, we perform a detailed constraint on the afterglow parameters for the FRB 131104/Swift J0644.5-5111 system. We find that for the commonly used microphysics shock parameters (e.g., {ε }e=0.1, {ε }B=0.01, and p = 2.3), if the fast radio burst (FRB) is indeed cosmological as inferred from its measured dispersion measure (DM), the ambient medium number density should be ≤slant {10}-3 {{cm}}-3, which is the typical value for a compact binary merger environment but disfavors a massive star origin. Assuming a typical ISM density, one would require that the redshift of the FRB be much smaller than the value inferred from DM (z\\ll 0.1), implying a non-cosmological origin of DM. The constraints are much looser if one adopts smaller {ε }B and {ε }e values, as observed in some gamma-ray burst afterglows. The FRB 131104/Swift J0644.5-5111 association remains plausible. We critically discuss possible progenitor models for the system.

  1. SWIFT Discovery of Gamma-ray Bursts without Jet Break Feature in their X-ray Afterglows

    NASA Technical Reports Server (NTRS)

    Sato, G.; Yamazaki, R.; Sakamoto, T.; Takahashi, T; Nakazawa, K.; Nakamura, T.; Toma, K.; Hullinger, D.; Tashiro, M.; Parsons, A. M.; Krimm, H. A.; Barthelmy, S. D.; Gehrels, N.; Burrows, D. N.; O'Brien, P. T.; Osborne, J. P.; Chincarini, G.; Lamb, D. Q.

    2007-01-01

    We analyze Swift gamma-ray bursts (GRBs) and X-ray afterglows for three GRBs with spectroscopic redshift determinations - GRB 050401, XRF 050416a, and GRB 050525a. We find that the relation between spectral peak energy and isotropic energy of prompt emissions (the Amati relation) is consistent with that for the bursts observed in pre-Swift era. However, we find that the X-ray afterglow lightcurves, which extend up to 10 - 70 days, show no sign of the jet break that is expected in the standard framework of collimated outflows. We do so by showing that none of the X-ray afterglow lightcurves in our sample satisfies the relation between the spectral and temporal indices that is predicted for the phase after jet break. The jet break time can be predicted by inverting the tight empirical relation between the peak energy of the spectrum and the collimation-corrected energy of the prompt emission (the Ghirlanda relation). We find that there are no temporal breaks within the predicted time intervals in X-ray band. This requires either that the Ghirlanda relation has a larger scatter than previously thought, that the temporal break in X-rays is masked by some additional source of X-ray emission, or that it does not happen because of some unknown reason.

  2. Electrical characterization of the flowing afterglow of N{sub 2} and N{sub 2}/O{sub 2} microwave plasmas at reduced pressure

    SciTech Connect

    Afonso Ferreira, J.; Stafford, L. Leonelli, R.; Ricard, A.

    2014-04-28

    A cylindrical Langmuir probe was used to analyze the spatial distribution of the number density of positive ions and electrons as well as the electron energy distribution function (EEDF) in the flowing afterglow of a 6 Torr N{sub 2} and N{sub 2}/O{sub 2} plasma sustained by a propagating electromagnetic surface wave in the microwave regime. In pure N{sub 2} discharges, ion densities were in the mid 10{sup 14} m{sup −3} in the pink afterglow and in the mid 10{sup 12} m{sup −3} early in the late afterglow. In both pink and late afterglows, the ion population was much higher than the electron population, indicating non-macroscopically neutral media. The EEDF was close to a Maxwellian with an electron temperature of 0.5 ± 0.1 eV, except in the pink afterglow where the temperature rose to 1.1 ± 0.2 eV. This latter behavior is ascribed to N{sub 2} vibration-vibration pumping in the pink afterglow that increases the concentration of high N{sub 2} vibrational states and thus rises the electron temperature by vibration-electron collisions. After addition of small amounts of O{sub 2} in the nominally pure N{sub 2} discharge, the charged particles densities and average electron energy first strongly increased and then decreased with increasing O{sub 2} concentration. Based on these data and the evolution of the N{sub 2}{sup +}(B) band emission intensities, it is concluded that a significant change in the positive ion composition of the flowing afterglow occurs, going from N{sub 2}{sup +} in nominally pure N{sub 2} discharges to NO{sup +} after addition of trace amounts of O{sub 2} in N{sub 2}.

  3. GEMINI SPECTROSCOPY OF THE SHORT-HARD GAMMA-RAY BURST GRB 130603B AFTERGLOW AND HOST GALAXY

    SciTech Connect

    Cucchiara, A.; Prochaska, J. X.; Werk, J.; Cenko, S. B.; Cardwell, A.; Turner, J.; Bloom, J. S.; Cobb, B. E.

    2013-11-10

    We present early optical photometry and spectroscopy of the afterglow and host galaxy of the bright short-duration gamma-ray burst GRB 130603B discovered by the Swift satellite. Using our Target of Opportunity program on the Gemini South telescope, our prompt optical spectra reveal a strong trace from the afterglow superimposed on continuum and emission lines from the z = 0.3568 ± 0.0005 host galaxy. The combination of a relatively bright optical afterglow (r' = 21.52 at Δt = 8.4 hr), together with an observed offset of 0.''9 from the host nucleus (4.8 kpc projected distance at z = 0.3568), allow us to extract a relatively clean spectrum dominated by afterglow light. Furthermore, the spatially resolved spectrum allows us to constrain the properties of the explosion site directly, and compare these with the host galaxy nucleus, as well as other short-duration GRB host galaxies. We find that while the host is a relatively luminous (L∼0.8 L{sup *}{sub B}), star-forming (SFR = 1.84 M{sub ☉} yr{sup –1}) galaxy with almost solar metallicity, the spectrum of the afterglow exhibits weak Ca II absorption features but negligible emission features. The explosion site therefore lacks evidence of recent star formation, consistent with the relatively long delay time distribution expected in a compact binary merger scenario. The star formation rate (SFR; both in an absolute sense and normalized to the luminosity) and metallicity of the host are both consistent with the known sample of short-duration GRB hosts and with recent results which suggest GRB 130603B emission to be the product of the decay of radioactive species produced during the merging process of a neutron-star-neutron-star binary ({sup k}ilonova{sup )}. Ultimately, the discovery of more events similar to GRB 130603B and their rapid follow-up from 8 m class telescopes will open new opportunities for our understanding of the final stages of compact-objects binary systems and provide crucial information

  4. A deep search for the host galaxies of gamma-ray bursts with no detected optical afterglow

    NASA Astrophysics Data System (ADS)

    Rossi, A.; Klose, S.; Ferrero, P.; Greiner, J.; Arnold, L. A.; Gonsalves, E.; Hartmann, D. H.; Updike, A. C.; Kann, D. A.; Krühler, T.; Palazzi, E.; Savaglio, S.; Schulze, S.; Afonso, P. M. J.; Amati, L.; Castro-Tirado, A. J.; Clemens, C.; Filgas, R.; Gorosabel, J.; Hunt, L. K.; Küpcü Yoldaş, A.; Masetti, N.; Nardini, M.; Nicuesa Guelbenzu, A.; Olivares, F. E.; Pian, E.; Rau, A.; Schady, P.; Schmidl, S.; Yoldaş, A.; de Ugarte Postigo, A.

    2012-09-01

    Context. Gamma-ray bursts (GRBs) can provide information about star formation at high redshifts. Even in the absence of a bright optical/near-infrared/radio afterglow, the high detection rate of X-ray afterglows by Swift/XRT and its localization precision of 2-3 arcsec facilitates the identification and the study of GRB host galaxies. Aims: We focus on the search for the host galaxies of 17 bursts with arcsec-sized XRT error circles but no detected long-wavelength afterglow, in spite of their deep and rapid follow-up observations. Three of these events can also be classified as truly dark bursts, i.e., the observed upper limit on the optical flux of the afterglow was less than expected based on the measured X-ray flux. Our goals are to identify the GRB host galaxy candidates and characterize their phenomenological parameters. Methods: Our study is based on deep RC and Ks-band observations performed with FORS1, FORS2, VIMOS, ISAAC, and HAWK-I at the ESO/VLT, partly supported by observations with the seven-channel imager GROND at the 2.2-m telescope on La Silla, and supplemented by observations with NEWFIRM at the 4-m telescope on Kitt Peak. To be conservative, we searched for host galaxy candidates within an area of twice the radius of each associated 90% c.l. Swift/XRT error circle. Results: For 15 of the 17 bursts, we find at least one galaxy within the searching area, and in the remaining two cases only a deep upper limit to RC and Ks can be provided. In seven cases, we discover extremely red objects in the error circles, at least four of which might be dust-enshrouded galaxies. The most remarkable case is the host of GRB 080207, which has a color of (RC - Ks)AB ~ 4.7 mag, and is one of the reddest galaxies ever associated with a GRB. As a by-product of our study we identify the optical afterglow of GRB 070517. Conclusions: Only a minority of optically dim afterglows are due to Lyman dropout (≲ 1/3). Extinction by dust in the host galaxies might explain all

  5. On the Color Indices and Absolute Brightnesses of the Optical Afterglows of GRB

    NASA Astrophysics Data System (ADS)

    Šimon, V.; Hudec, R.; Masetti, N.; Pizzichini, G.

    2003-04-01

    The study of the color indices and luminosities of 17 optical afterglows (OAs) of GRBs, including the most recent one, GRB010222, showed that the color variations during the decline of OAs are quite small during t - T0 < 10 days and allow a comparison among them, even for the less densely sampled OAs. The colors in the observer frame concentrate at (V - R)0 = 0.40+/-0.13, (R - I)0 = 0.46+/-0.18, (B - V)0 = 0.47+/-0.17, except for GRB000131 and GRB980425. However, large scatter is observed in (U - B)0. The color evolution of the OAs is negligible although their brightness declines by several magnitudes during t - T0 < 10 days. Such a strong concentration of the color indices also suggests that the intrinsic reddening (inside their host galaxies) must be quite similar and relatively small for all these events. The absolute brightness of OAs in the observer frame lies within MR0 = -26.5 to -22.2 for (t - T0)rest = 0.25 days. The general decline rate of the OA sample considered here seems to be independent of the absolute optical brightness of the OA, measured at some t - T0 identical for all OAs, and the light curves of all events are almost parallel, when corrected for the redshift-induced time dilation.

  6. An external-shock model for gamma-ray burst afterglow 130427A

    NASA Astrophysics Data System (ADS)

    Panaitescu, A.; Vestrand, W. T.; Woźniak, P.

    2013-12-01

    The complex multiwavelength emission of gamma-ray burst (GRB) afterglow 130427A (monitored in the radio up to 10 d, in the optical and X-ray until 50 d, and at GeV energies until 1 d) can be accounted for by a hybrid reverse-forward shock synchrotron model, with inverse-Compton emerging only above a few GeV. The high ratio of the early optical to late radio flux requires that the ambient medium is a wind and that the forward-shock synchrotron spectrum peaks in the optical at about 10 ks. The latter has two consequences: the wind must be very tenuous and the optical emission before 10 ks must arise from the reverse-shock, as suggested also by the bright optical flash that Raptor has monitored during the prompt emission phase (<100 s). The Very Large Array radio emission is from the reverse-shock, the Swift X-ray emission is mostly from the forward-shock, but the both shocks give comparable contributions to the Fermi GeV emission. The weak wind implies a large blast-wave radius (8 t_day^{1/2} pc), which requires a very tenuous circumstellar medium, suggesting that the massive stellar progenitor of GRB 130427A resided in a superbubble.

  7. Measurement of proton transfer reaction rates in a microwave cavity discharge flowing afterglow

    NASA Astrophysics Data System (ADS)

    Brooke, George M., IV

    The reaction rate coefficients between the hydronium ion and the molecules ethene (C2H4), propene (C 3H6), 1-butene (C4H8) and hydrogen sulfide (H2S) were measured at 296 K. The measured reaction rates were compared to collision rates calculated using average dipole orientation (ADO) theory. Reaction efficiency depends primarily upon the proton affinity of the molecules. All the measurements were obtained using the newly developed microwave cavity discharge flowing afterglow (MCD-FA) apparatus. This device uses an Asmussen-type microwave cavity discharge ion source that is spatially separated from the flow tube, eliminating many of the problems inherent with the original FA devices. In addition to measuring reaction rate coefficients, the MCD-FA was shown to be an effective tool for measuring trace compounds in atmospheric air. This method has many advantages over current detection techniques since compounds can be detected in almost real time, large mass ranges can be scanned quickly, and repeated calibration is not required. Preliminary measurements were made of car exhaust and exhaled alveolar air. Car exhaust showed the presence of numerous hydrocarbons, such as butene, benzene and toluene while the exhaled alveolar air showed the presence of various volatile organic compounds such as methanol and acetone.

  8. X-RAY SPECTRAL COMPONENTS OBSERVED IN THE AFTERGLOW OF GRB 130925A

    SciTech Connect

    Bellm, Eric C.; Forster, Karl; Harrison, Fiona A.; Madsen, Kristin K.; Perley, Daniel A.; Rana, Vikram R.; Barrière, Nicolas M.; Boggs, Steven E.; Craig, William W.; Bhalerao, Varun; Cenko, S. Bradley; Christensen, Finn E.; Fryer, Chris L.; Hailey, Charles J.; Horesh, Assaf; Ofek, Eran O.; Kouveliotou, Chryssa; Reynolds, Stephen P.; Stern, Daniel; and others

    2014-04-01

    We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at >4σ significance, and its spectral shape varies between two observation epochs at 2 × 10{sup 5} and 10{sup 6} s after the burst. Several models can fit this additional component, each with very different physical implications. A broad, resolved Gaussian absorption feature of several keV width improves the fit, but it is poorly constrained in the second epoch. An additive blackbody or second power-law component provide better fits. Both are challenging to interpret: the blackbody radius is near the scale of a compact remnant (10{sup 8} cm), while the second power-law component requires an unobserved high-energy cutoff in order to be consistent with the non-detection by Fermi/Large Area Telescope.

  9. MITSuME: multicolor optical/NIR telescopes for GRB afterglows

    SciTech Connect

    Shimokawabe, Takashi; Kawai, Nobuyuki; Kotani, Taro; Yatsu, Yoichi; Ishimura, Takuto; Vasquez, Nicolas; Mori, Yuki; Kudo, Yusuke; Yoshida, Michitoshi; Yanagisawa, Kenshi; Nagayama, Shogo; Toda, Hiroyuki; Shimozu, Yasuhiro; Kuroda, Daisuke; Watanabe, Junichi; Fukushima, Hideo; Mori, Masaki

    2008-05-22

    Multicolor Imaging Telescopes for Survey and Monstrous Explosions (MITSuME) is built to perform multi-color photometry of NIR/optical afterglow covering the wavebands from K{sub s} to g' allowing the photometric redshift measurements up to z{approx_equal}10.Two 50 cm optical telescopes are built at Akeno, Yamanashi in eastern Japan, and at OAO, Okayama in western Japan. Each telescope has a Tricolor Camera, which allows us to take simultaneous images in g', R{sub c} and I{sub c} bands. These telescopes respond to GCN alerts and start taking series of tricolor images, which are immediately processed through the analys is pipeline on site. The pipeline consists of source finding, catalog matching, sky coordinates mapping to the image pixels, and photometry of the found sources. In addition, an automated search for an optical counterpart is performed.In addition, a wide-field (1 deg.) 91 cm NIR telescope is being built at OAO with filters in K{sub s}, H, J, and y bands.Summary of early results will be also presented.

  10. Linear and circular polarization in ultra-relativistic synchrotron sources - implications to GRB afterglows

    NASA Astrophysics Data System (ADS)

    Nava, Lara; Nakar, Ehud; Piran, Tsvi

    2016-01-01

    Polarization measurements from relativistic outflows are a valuable tool to probe the geometry of the emission region and the microphysics of the particle distribution. Indeed, the polarization level depends on (i) the local magnetic field orientation, (ii) the geometry of the emitting region with respect to the line of sight and (iii) the electron pitch angle distribution. Here we consider optically thin synchrotron emission and we extend the theory of circular polarization from a point source to an extended radially expanding relativistic jet. We present numerical estimates for both linear and circular polarization in such systems. We consider different configurations of the magnetic field, spherical and jetted outflows, isotropic and anisotropic pitch angle distributions, and outline the difficulty in obtaining the reported high level of circular polarization observed in the afterglow of Gamma Ray Burst (GRB) 121024A. We conclude that the origin of the observed polarization cannot be intrinsic to an optically thin synchrotron process, even when the electron pitch angle distribution is extremely anisotropic.

  11. Effect of humidity on gas temperature in the afterglow of pulsed positive corona discharge

    NASA Astrophysics Data System (ADS)

    Ono, Ryo; Teramoto, Yoshiyuki; Oda, Tetsuji

    2010-01-01

    The effects of humidity on gas temperature in the afterglow of a pulsed positive corona discharge are studied. The gas temperature is measured using the laser-induced fluorescence (LIF) of NO molecules. The discharge occurs in a 13 mm point-to-plane gap under atmospheric pressure. When the water vapor concentration in air is increased from 0.5% to 2.4%, the temperature increases from 550 to 850 K near the anode tip, and from 350 to 650 K at a position 2.5 mm from the anode tip. The gas heating in the humid environment is due to the fast vibration-to-vibration processes of the O2-H2O and N2-H2O systems and the extremely rapid vibration-to-translation process of the H2O-H2O system. These processes accelerate the transfer of energy from O2(v) and N2(v) to translational energy. Measurements of the LIF of O2(v = 6) show that the decay rate of O2(v) density is increased by humidification.

  12. X-Ray Spectral Components Observed in the Afterglow of GRB 130925A

    NASA Technical Reports Server (NTRS)

    Bellm, Eric C.; Barriere, Nicolas M.; Bhalerao, Varun; Boggs, Steven E.; Cenko, S. Bradley; Christensen, Finn E.; Craig, William W.; Forster, Karl; Fryer, Chris L.; Hailey, Charles J.; Harrison, Fiona A.; Horesh, Assaf; Kouveliotou, Chryssa; Madsen, Kristin K.; Miller, Jon M.; Ofek, Eran O.; Perley, Daniel A.; Rana, Vikram R.; Miller, Jon M.; Stern, Daniel; Tomsick, John A.; Zhang, William W.

    2014-01-01

    We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at greater than 4 less than 1 significance, and its spectral shape varies between two observation epochs at 2 x 10 (sup 5) and 10 (sup 6) seconds after the burst. Several models can fit this additional component, each with very different physical implications. A broad, resolved Gaussian absorption feature of several kiloelectronvolts width improves the fit, but it is poorly constrained in the second epoch. An additive blackbody or second power-law component provide better fits. Both are challenging to interpret: the blackbody radius is near the scale of a compact remnant (10 (sup 8) centimeters), while the second power-law component requires an unobserved high-energy cutoff in order to be consistent with the non-detection by Fermi/Large Area Telescope.

  13. The effect of a direct current field on the microparticle charge in the plasma afterglow

    SciTech Connect

    Wörner, L.; Ivlev, A. V.; Huber, P.; Hagl, T.; Thomas, H. M.; Morfill, G. E.; Couëdel, L.; Schwabe, M.; Mikikian, M.; Boufendi, L.; Skvortsov, A.; Lipaev, A. M.; Molotkov, V. I.; Petrov, O. F.; Fortov, V. E.

    2013-12-15

    Residual charges of individual microparticles forming dense clouds were measured in a RF discharge afterglow. Experiments were performed under microgravity conditions on board the International Space Station, which ensured particle levitation inside the gas volume after the plasma switch-off. The distribution of residual charges as well as the spatial distribution of charged particles across the cloud were analyzed by applying a low-frequency voltage to the electrodes and measuring amplitudes of the resulting particle oscillations. Upon “free decharging” conditions, the charge distribution had a sharp peak at zero and was rather symmetric (with charges concentrated between −10e and +10e), yet positively and negatively charged particles were homogeneously distributed over the cloud. However, when decharging evolved in the presence of an external DC field (applied shortly before the plasma switch-off) practically all residual charges were positive. In this case, the overall charge distribution had a sharp peak at about +15e and was highly asymmetric, while the spatial distribution exhibited a significant charge gradient along the direction of the applied DC field.

  14. Dissociative recombination of HCl(+), H2Cl(+), DCl(+), and D2Cl(+) in a flowing afterglow.

    PubMed

    Wiens, Justin P; Miller, Thomas M; Shuman, Nicholas S; Viggiano, Albert A

    2016-12-28

    Dissociative recombination of electrons with HCl(+), H2Cl(+), DCl(+), and D2Cl(+) has been measured under thermal conditions at 300, 400, and 500 K using a flowing afterglow-Langmuir probe apparatus. Measurements for HCl(+) and DCl(+) employed the variable electron and neutral density attachment mass spectrometry (VENDAMS) method, while those for H2Cl(+) and D2Cl(+) employed both VENDAMS and the more traditional technique of monitoring electron density as a function of reaction time. At 300 K, HCl(+) and H2Cl(+) recombine with kDR = 7.7±2.1(4.5) × 10(-8) cm(3) s(-1) and 2.6 ± 0.8 × 10(-7) cm(3) s(-1), respectively, whereas D2Cl(+) is roughly half as fast as H2Cl(+) with kDR = 1.1 ± 0.3 × 10(-7) cm(3) s(-1) (2σ confidence intervals). DCl(+) recombines with a rate coefficient below the approximate detection limit of the method (≲5 × 10(-8) cm(3) s(-1)) at all temperatures. Relatively slow dissociative recombination rates have been speculated to be responsible for the large HCl(+) and H2Cl(+) abundances in interstellar clouds compared to current astrochemical models, but our results imply that the discrepancy must originate elsewhere.

  15. A new technique for studying ion-ion recombination in a flowing afterglow Langmuir probe apparatus

    NASA Astrophysics Data System (ADS)

    Miller, Thomas M.; Friedman, Jeffrey F.; Viggiano, A. A.

    2007-11-01

    We present a new technique for measuring ion-ion recombination rate constants in a flowing afterglow Langmuir probe (FALP) apparatus. The technique involves measuring the fractional negative ion product distribution following electron attachment versus the initial electron density when two or more products are formed. The concentration of reactant gas is kept low enough that the plasma retains its electron-Ar+, ambipolar diffusion character along the entire length of the flow tube. If only polyatomic anions are formed, accurate relative rates are obtained. When one of the species is atomic, absolute rates are also possible by doing a detailed model of the plasma kinetics. Here we present rate constants for Ar+ recombining with Cl2- ((5.3 ± 1.6) × 10-8 cm3 s-1 at 302 K), Br2- ((3.9 ± 1.2) × 10-8 cm3 s-1 at 302 K), the phosgene negative ion CCl2O- ((8.9 ± 2.7) × 10-8 cm3 s-1 at 302 K), and relative rate constants for Ar+ + SF6- and SF5- (ratio 1.2 at 550 K, with an uncertainty of +0.3 and -0.1). The diatomic negative ions are found to recombine slower than the polyatomic ones, in agreement with earlier indications.

  16. A possible macronova in the late afterglow of the long–short burst GRB 060614

    PubMed Central

    Yang, Bin; Jin, Zhi-Ping; Li, Xiang; Covino, Stefano; Zheng, Xian-Zhong; Hotokezaka, Kenta; Fan, Yi-Zhong; Piran, Tsvi; Wei, Da-Ming

    2015-01-01

    Long-duration (>2 s) γ-ray bursts that are believed to originate from the death of massive stars are expected to be accompanied by supernovae. GRB 060614, that lasted 102 s, lacks a supernova-like emission down to very stringent limits and its physical origin is still debated. Here we report the discovery of near-infrared bump that is significantly above the regular decaying afterglow. This red bump is inconsistent with even the weakest known supernova. However, it can arise from a Li-Paczyński macronova—the radioactive decay of debris following a compact binary merger. If this interpretation is correct, GRB 060614 arose from a compact binary merger rather than from the death of a massive star and it was a site of a significant production of heavy r-process elements. The significant ejected mass favours a black hole–neutron star merger but a double neutron star merger cannot be ruled out. PMID:26065563

  17. The effect of a direct current field on the microparticle charge in the plasma afterglow

    NASA Astrophysics Data System (ADS)

    Wörner, L.; Ivlev, A. V.; Couëdel, L.; Huber, P.; Schwabe, M.; Hagl, T.; Mikikian, M.; Boufendi, L.; Skvortsov, A.; Lipaev, A. M.; Molotkov, V. I.; Petrov, O. F.; Fortov, V. E.; Thomas, H. M.; Morfill, G. E.

    2013-12-01

    Residual charges of individual microparticles forming dense clouds were measured in a RF discharge afterglow. Experiments were performed under microgravity conditions on board the International Space Station, which ensured particle levitation inside the gas volume after the plasma switch-off. The distribution of residual charges as well as the spatial distribution of charged particles across the cloud were analyzed by applying a low-frequency voltage to the electrodes and measuring amplitudes of the resulting particle oscillations. Upon "free decharging" conditions, the charge distribution had a sharp peak at zero and was rather symmetric (with charges concentrated between -10e and +10e), yet positively and negatively charged particles were homogeneously distributed over the cloud. However, when decharging evolved in the presence of an external DC field (applied shortly before the plasma switch-off) practically all residual charges were positive. In this case, the overall charge distribution had a sharp peak at about +15e and was highly asymmetric, while the spatial distribution exhibited a significant charge gradient along the direction of the applied DC field.

  18. SHOCK CORRUGATION BY RAYLEIGH-TAYLOR INSTABILITY IN GAMMA-RAY BURST AFTERGLOW JETS

    SciTech Connect

    Duffell, Paul C.; MacFadyen, Andrew I. E-mail: macfadyen@nyu.edu

    2014-08-10

    Afterglow jets are Rayleigh-Taylor unstable and therefore turbulent during the early part of their deceleration. There are also several processes which actively cool the jet. In this Letter, we demonstrate that if cooling significantly increases the compressibility of the flow, the turbulence collides with the forward shock, destabilizing and corrugating it. In this case, the forward shock is turbulent enough to produce the magnetic fields responsible for synchrotron emission via small-scale turbulent dynamo. We calculate light curves assuming the magnetic field is in energy equipartition with the turbulent kinetic energy and discover that dynamic magnetic fields are well approximated by a constant magnetic-to-thermal energy ratio of 1%, though there is a sizeable delay in the time of peak flux as the magnetic field turns on only after the turbulence has activated. The reverse shock is found to be significantly more magnetized than the forward shock, with a magnetic-to-thermal energy ratio of the order of 10%. This work motivates future Rayleigh-Taylor calculations using more physical cooling models.

  19. NO FLARES FROM GAMMA-RAY BURST AFTERGLOW BLAST WAVES ENCOUNTERING SUDDEN CIRCUMBURST DENSITY CHANGE

    SciTech Connect

    Gat, Ilana; Van Eerten, Hendrik; MacFadyen, Andrew

    2013-08-10

    Afterglows of gamma-ray bursts are observed to produce light curves with the flux following power-law evolution in time. However, recent observations reveal bright flares at times on the order of minutes to days. One proposed explanation for these flares is the interaction of a relativistic blast wave with a circumburst density transition. In this paper, we model this type of interaction computationally in one and two dimensions, using a relativistic hydrodynamics code with adaptive mesh refinement called RAM, and analytically in one dimension. We simulate a blast wave traveling in a stellar wind environment that encounters a sudden change in density, followed by a homogeneous medium, and compute the observed radiation using a synchrotron model. We show that flares are not observable for an encounter with a sudden density increase, such as a wind termination shock, nor for an encounter with a sudden density decrease. Furthermore, by extending our analysis to two dimensions, we are able to resolve the spreading, collimation, and edge effects of the blast wave as it encounters the change in circumburst medium. In all cases considered in this paper, we find that a flare will not be observed for any of the density changes studied.

  20. Prompt and Afterglow Emission Properties of Gamma-Ray Bursts with Spectroscopically Identified Supernovae

    SciTech Connect

    Kaneko, Yuki; Ramirez-Ruiz, E.; Granot, J.; Kouveliotou, C.; Woosley, S.E.; Patel, S.K.; Rol, E.; Zand, J.J.M.in't; a; Wijers, R.A.M.J.; Strom, R.; /USRA, Huntsville /Princeton, Inst. Advanced Study /UC, Santa Cruz /KIPAC, Menlo Park /NASA, Marshall /Leicester U. /SRON, Utrecht /Utrecht, Astron. Inst. /Amsterdam U., Astron. Inst. /NFRA, Dwingeloo

    2006-07-12

    We present a detailed spectral analysis of the prompt and afterglow emission of four nearby long-soft gamma-ray bursts (GRBs 980425, 030329, 031203, and 060218) that were spectroscopically found to be associated with type Ic supernovae, and compare them to the general GRB population. For each event, we investigate the spectral and luminosity evolution, and estimate the total energy budget based upon broadband observations. The observational inventory for these events has become rich enough to allow estimates of their energy content in relativistic and sub-relativistic form. The result is a global portrait of the effects of the physical processes responsible for producing long-soft GRBs. In particular, we find that the values of the energy released in mildly relativistic outflows appears to have a significantly smaller scatter than those found in highly relativistic ejecta. This is consistent with a picture in which the energy released inside the progenitor star is roughly standard, while the fraction of that energy that ends up in highly relativistic ejecta outside the star can vary dramatically between different events.

  1. GRB 020410: A Gamma-ray burst afterglow discovered by its supernova light

    SciTech Connect

    Levan, Andrew; Nugent, Peter; Fruchter, Andrew; Burud, Ingunn; Branch, David; Rhoads, James; Castro-Tirado, Alberto; Gorosabel, Javier; Ceron, Jose Maria Castro; Thorsett, Stephen E.; Kouveliotou, Chryssa; Golenetskii, Sergey; Fynbo, Johan; Garnavich, Peter; Holland, Stephen; Hjorth, Jens; Moller, Palle; Pian, Elena; Tanvir, Nial; Ulanov, Mihail; Wijers, Ralph; Woosley, Stan

    2004-03-19

    We present the discovery and monitoring of the optical transient (OT) associated with GRB 020410. The fading OT was found by Hubble Space Telescope (HST) observations taken 28 and 65 days after burst at a position consistent with the X-ray afterglow. Subsequent re-examination of early ground based observations revealed that a faint OT was present 6 hours after burst, confirming the source association with GRB 020410. A deep non-detection after one week requires that the OT re-brightened between day 7 and day 28, and further late time HST data taken approximately 100 days after burst imply that it is very red (F{sub nu} proportional to nu-2.7). We compare both the flux and color of the excess with supernova models and show that the data are best explained by the presence of a Type I b/c supernova at a redshift z approx. equal 0.5, which occurred roughly coincident with the day of GRB.

  2. Self-organized criticality in X-ray flares of gamma-ray-burst afterglows

    NASA Astrophysics Data System (ADS)

    Wang, F. Y.; Dai, Z. G.

    2013-08-01

    X-ray flares detected in nearly half of gamma-ray-burst (GRB) afterglows are one of the most intriguing phenomena in high-energy astrophysics. All of the observations indicate that the central engines of bursts, after the gamma-ray emission has ended, still have long periods of activity, during which energetic explosions eject relativistic materials, leading to late-time X-ray emission. It is thus expected that X-ray flares provide important clues as to the nature of the central engines of GRBs, and more importantly, unveil the physical mechanism of the flares themselves, which has so far remained mysterious. Here we report statistical results of X-ray flares of GRBs with known redshifts, and show that X-ray flares and solar flares share three statistical properties: power-law frequency distributions for energies, durations and waiting times. All of the distributions can be well understood within the physical framework of a self-organized criticality (SOC) system. The statistical properties of X-ray flares of GRBs are similar to solar flares, and thus both can be attributed to a SOC process. Both types of flares may be driven by a magnetic reconnection process, but X-ray flares of GRBs are produced in ultra-strongly magnetized millisecond pulsars or long-term hyperaccreting disks around stellar-mass black holes.

  3. The 'Supercritical Pile' GRB Model: Afterglows and GRB, XRR, XRF Unification

    NASA Technical Reports Server (NTRS)

    Kazanas, D.

    2007-01-01

    We present the general notions and observational consequences of the "Supercritical Pile" GRB model; the fundamental feature of this model is a detailed process for the conversion of the energy stored in relativistic protons in the GRB Relativistic Blast Waves (RBW) into relativistic electrons and then into radiation. The conversion is effected through the $p \\, \\gamma \\rightarrow p \\, e circumflex + e circumflex -$ reaction, whose kinematic threshold is imprinted on the GRB spectra to provide a peak of their emitted luminosity at energy \\Ep $\\sim 1$ MeV in the lab frame. We extend this model to include, in addition to the (quasi--)thermal relativistic post-shock protons an accelerated component of power law form. This component guarantees the production of $e circumflex +e circumflex- - $pairs even after the RBW has slowed down to the point that its (quasi-) thermal protons cannot fulfill the threshold of the above reaction. We suggest that this last condition marks the transition from the prompt to the afterglow GRB phase. We also discuss conditions under which this transition is accompanied by a significant drop in the flux and could thus account for several puzzling, recent observations. Finally, we indicate that the same mechanism applied to the late stages of the GRB evolution leads to a decrease in \\Ep $\\propto \\Gamma circumflex 2(t)\\propto t circumflex {-3/4}$, a feature amenable to future observational tests.

  4. Probing a Gamma-Ray Burst Progenitor at a Redshift of z = 2: A Comprehensive Observing Campaign Campaign of the Afterglow of GRB 030226

    NASA Technical Reports Server (NTRS)

    Klose, S.; Greiner, J.; Rau, A.; Henden, A. A.; Hartmann, D. H.; Zeh, A.; Ries, C.; Masetti, N.; Malesani, D.; Guenther, E.

    2004-01-01

    We report results from a comprehensive follow-up observing campaign of the afterglow of GRB 030226 including VLT spectroscopy, VLT polarimetry, and Chandra X-ray observations. In addition, we present BOOTES-1 wide-field observations at the time of the occurrence of the burst. First observations at ESO started 0.2 days after the event when the gamma ray burst (GRB) afterglow was at a magnitude of R approximately 19 and continued until the afterglow had faded below the detection threshold (R greater than 26). No underlying host galaxy was found. The optical light curve shows a break around 0.8 days after the burst, which is achromatic within the observational errors, supporting the view that it was due to a jetted explosion. Close to the break time the degree of linear polarization of the afterglow light was less than 1.1%, which favors a uniform-jet model rather than a structured one. VLT spectra show two absorption line systems at redshifts z = 1.962 plus or minus 0.001 and 1.986 plus or minus 0.001, placing the lower limit for the redshift of the GRB close to 2. We emphasize that the kinematics and the composition of the absorbing clouds responsible for these line systems are very similar to those observed in the afterglow of GRB 021004. This corroborates the picture in which at least some GRBs are physically related to the explosion of a Wolf-Rayet star.

  5. THE ROLE OF NEWLY BORN MAGNETARS IN GAMMA-RAY BURST X-RAY AFTERGLOW EMISSION: ENERGY INJECTION AND INTERNAL EMISSION

    SciTech Connect

    Yu Yunwei; Cheng, K. S.; Cao Xiaofeng E-mail: hrspksc@hkucc.hku.h

    2010-05-20

    Swift observations suggest that the central compact objects of some gamma-ray bursts (GRBs) could be newly born millisecond magnetars. Therefore, considering the spin evolution of the magnetars against r-mode instability, we investigate the role of magnetars in GRB X-ray afterglow emission. Besides modifying the conventional energy injection model, we pay particular attention to the internal X-ray afterglow emission, whose luminosity is assumed to track the magnetic dipole luminosity of the magnetars with a certain fraction. Following a comparison between the model and some selected observational samples, we suggest that some so-called canonical X-ray afterglows including the shallow decay, normal decay, and steeper-than-normal decay phases could be internally produced by the magnetars (possibly through some internal dissipations of the magnetar winds), while the (energized) external shocks are associated with another type of X-ray afterglows. If this is true, then from those internal X-ray afterglows we can further determine the magnetic field strengths and the initial spin periods of the corresponding magnetars.

  6. NuSTAR OBSERVATIONS OF GRB 130427A ESTABLISH A SINGLE COMPONENT SYNCHROTRON AFTERGLOW ORIGIN FOR THE LATE OPTICAL TO MULTI-GEV EMISSION

    SciTech Connect

    Kouveliotou, C.; Racusin, J. L.; Gehrels, N.; McEnery, J. E.; Zhang, W. W.; Bellm, E.; Harrison, F. A.; Vianello, G.; Oates, S.; Fryer, C. L.; Boggs, S. E.; Craig, W. W.; Christensen, F. E.; Dermer, C. D.; Hailey, C. J.; Melandri, A.; Tagliaferri, G.; Mundell, C. G.; Stern, D. K. E-mail: granot@openu.ac.il

    2013-12-10

    GRB 130427A occurred in a relatively nearby galaxy; its prompt emission had the largest GRB fluence ever recorded. The afterglow of GRB 130427A was bright enough for the Nuclear Spectroscopic Telescope ARray (NuSTAR) to observe it in the 3-79 keV energy range long after its prompt emission (∼1.5 and 5 days). This range, where afterglow observations were previously not possible, bridges an important spectral gap. Combined with Swift, Fermi, and ground-based optical data, NuSTAR observations unambiguously establish a single afterglow spectral component from optical to multi-GeV energies a day after the event, which is almost certainly synchrotron radiation. Such an origin of the late-time Fermi/Large Area Telescope >10 GeV photons requires revisions in our understanding of collisionless relativistic shock physics.

  7. Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties: Luminescence Properties of Sr2SnO4:Sm3+ Afterglow Phosphor

    NASA Astrophysics Data System (ADS)

    Lei, Bing-Fu; Yue, Song; Zhang, Yong-Zhe; Liu, Ying-Liang

    2010-03-01

    A new long-lasting phosphorescence (LLP) phosphor, Sr2SnO4:Sm3+, which emits reddish-orange LLP upon UV-excitation, is prepared by a conventional high-temperature solid-state method. After irradiation under 247-nm UV light, Sr2SnO4:Sm3+ emits an intense reddish-orange emission afterglow from the 4G5/2 to 6HJ (J = 5/2, 7/2, 9/2) transitions. The afterglow decay curve of the Sm3+ -doped Sr2SnO4 phosphor contains a fast decay component and another slow decay one. Due to the presence of the slow decay component, the afterglow can be seen with the naked eye in the dark clearly for more than 1 h after removal of the excitation source.

  8. Ag/BiOBr Film in a Rotating-Disk Reactor Containing Long-Afterglow Phosphor for Round-the-Clock Photocatalysis.

    PubMed

    Yin, Haibo; Chen, Xiaofang; Hou, Rujing; Zhu, Huijuan; Li, Shiqing; Huo, Yuning; Li, Hexing

    2015-09-16

    Ag/BiOBr film coated on the glass substrate was synthesized by a solvothermal method and a subsequent photoreduction process. Such a Ag/BiOBr film was then adhered to a hollow rotating disk filled with long-afterglow phosphor inside the chamber. The Ag/BiOBr film exhibited high photocatalytic activity for organic pollutant degradation owing to the improved visible-light harvesting and the separation of photoinduced charges. The long-afterglow phosphor could absorb the excessive daylight and emit light around 488 nm, activating the Ag/BiOBr film to realize round-the-clock photocatalysis. Because the Ag nanoparticles could extend the light absorbance of the Ag/BiOBr film to wavelengths of around 500 nm via a surface plasma resonance effect, they played a key role in realizing photocatalysis induced by long-afterglow phosphor.

  9. Swift observations of GRB 060614: an anomalous burst with a well behaved afterglow

    NASA Astrophysics Data System (ADS)

    Mangano, V.; Holland, S. T.; Malesani, D.; Troja, E.; Chincarini, G.; Zhang, B.; La Parola, V.; Brown, P. J.; Burrows, D. N.; Campana, S.; Capalbi, M.; Cusumano, G.; Della Valle, M.; Gehrels, N.; Giommi, P.; Grupe, D.; Guidorzi, C.; Mineo, T.; Moretti, A.; Osborne, J. P.; Pandey, S. B.; Perri, M.; Romano, P.; Roming, P. W. A.; Tagliaferri, G.

    2007-07-01

    GRB 060614 is a remarkable gamma-ray burst (GRB) observed by Swift with puzzling properties, which challenge current progenitor models. In particular, the lack of any bright supernova (SN) down to very strict limits and the vanishing spectral lags during the whole burst are typical of short GRBs, strikingly at odds with the long (102 s) duration of this event. Here we present detailed spectral and temporal analysis of the Swift observations of GRB 060614. We show that the burst presents standard optical, ultraviolet and X-ray afterglows, detected beginning 4 ks after the trigger. An achromatic break is observed simultaneously in the optical and X-ray bands, at a time consistent with the break in the R-band light curve measured by the VLT. The achromatic behaviour and the consistent post-break decay slopes make GRB 060614 one of the best examples of a jet break for a Swift burst. The optical and ultraviolet afterglow light curves have also an earlier break at 29.7 ± 4.4 ks, marginally consistent with a corresponding break at 36.6 ± 2.4 ks observed in the X-rays. In the optical, there is strong spectral evolution around this break, suggesting the passage of a break frequency through the optical/ultraviolet band. The very blue spectrum at early times suggests this may be the injection frequency, as also supported by the trend in the light curves: rising at low frequencies, and decaying at higher energies. The early X-ray light curve (from 97 to 480 s) is well interpreted as the X-ray counterpart of the burst extended emission. Spectral analysis of the BAT and XRT data in the ~80 s overlap time interval show that the peak energy of the burst has decreased to as low as 8 keV at the beginning of the XRT observation. Spectral analysis of following XRT data shows that the peak energy of the burst continues to decrease through the XRT energy band and exits it at about 500 s after the trigger. The average peak energy Ep of the burst is likely below the BAT energy band (<24

  10. Radio afterglows of a complete sample of bright Swift GRBs: predictions from present days to the SKA era

    NASA Astrophysics Data System (ADS)

    Ghirlanda, G.; Salvaterra, R.; Burlon, D.; Campana, S.; Melandri, A.; Bernardini, M. G.; Covino, S.; D'Avanzo, P.; D'Elia, V.; Ghisellini, G.; Nava, L.; Prandoni, I.; Sironi, L.; Tagliaferri, G.; Vergani, S. D.; Wolter, A.

    2013-11-01

    Radio observations of Gamma-Ray Bursts (GRBs) afterglows are fundamental in providing insights into their physics and environment, and in constraining the true energetics of these sources. Nonetheless, radio observations of GRB afterglows are presently sparse in the time/frequency domain. Starting from a complete sample of 58 bright Swift long bursts (BAT6), we constructed a homogeneous sub-sample of 38 radio detections/upper limits which preserves all the properties of the parent sample. One half of the bursts have detections between 1 and 5 d after the explosion with typical fluxes F ≳ 100 μJy at 8.4 GHz. Through a Population SYnthesis Code coupled with the standard afterglow Hydrodynamical Emission model, we reproduce the radio flux distribution of the radio sub-sample. Based on these results, we study the detectability in the time/frequency domain of the entire long GRB population by present and future radio facilities. We find that the GRBs that typically trigger Swift can be detected at 8.4 GHz by Jansky Very Large Array within few days with modest exposures even at high redshifts. The final Square Kilometre Array (SKA) can potentially observe the whole GRB population provided that there will be a dedicated GRB gamma-ray detector more sensitive than Swift. For a sizeable fraction (50 per cent) of these bursts, SKA will allow us to perform radio calorimetry, after the trans-relativistic transition (occurring ˜100 d), providing an estimate of the true (collimation corrected) energetics of GRBs.

  11. DISCOVERY OF SMOOTHLY EVOLVING BLACKBODIES IN THE EARLY AFTERGLOW OF GRB 090618: EVIDENCE FOR A SPINE–SHEATH JET?

    SciTech Connect

    Basak, Rupal; Rao, A. R. E-mail: arrao@tifr.res.in

    2015-10-20

    GRB 090618 is a bright gamma-ray burst (GRB) with multiple pulses. It shows evidence of thermal emission in the initial pulses as well as in the early afterglow phase. Because high-resolution spectral data from the Swift/X-ray Telescope (XRT) are available for the early afterglow, we investigate the shape and evolution of the thermal component in this phase using data from the Swift/Burst Alert Telescope (BAT), the Swift/XRT, and the Fermi/Gamma-ray Burst Monitor detectors. An independent fit to the BAT and XRT data reveals two correlated blackbodies with monotonically decreasing temperatures. Hence, we investigated the combined data with a model consisting of two blackbodies and a power law (2BBPL), a model suggested for several bright GRBs. We elicit the following interesting features of the 2BBPL model: (1) the same model is applicable from the peak of the last pulse in the prompt emission to the afterglow emission, (2) the ratio of temperatures and the fluxes of the two blackbodies remains constant throughout the observations, (3) the blackbody temperatures and fluxes show a monotonic decrease with time, with the BB fluxes dropping about a factor of two faster than that of the power-law (PL) emission, and (4) attributing the blackbody emission to photospheric emissions, we find that the photospheric radii increase very slowly with time, and the lower-temperature blackbody shows a larger emitting radius than that of the higher-temperature blackbody. We find some evidence that the underlying shape of the nonthermal emission is a cutoff power law rather than a PL. We sketch a spine–sheath jet model to explain our observations.

  12. The radio afterglow of Swift J1644+57 reveals a powerful jet with fast core and slow sheath

    NASA Astrophysics Data System (ADS)

    Mimica, P.; Giannios, D.; Metzger, B. D.; Aloy, M. A.

    2015-07-01

    We model the non-thermal transient Swift J1644+57 as resulting from a relativistic jet powered by the accretion of a tidally disrupted star on to a supermassive black hole. Accompanying synchrotron radio emission is produced by the shock interaction between the jet and the dense circumnuclear medium, similar to a gamma-ray burst afterglow. An open mystery, however, is the origin of the late-time radio re-brightening, which occurred well after the peak of the jetted X-ray emission. Here, we systematically explore several proposed explanations for this behaviour by means of multidimensional hydrodynamic simulations coupled to a self-consistent radiative transfer calculation of the synchrotron emission. Our main conclusion is that the radio afterglow of Swift J1644+57 is not naturally explained by a jet with a one-dimensional top-hat angular structure. However, a more complex angular structure comprised of an ultrarelativistic core (Lorentz factor Γ ˜ 10) surrounded by a slower (Γ ˜ 2) sheath provides a reasonable fit to the data. Such a geometry could result from the radial structure of the super-Eddington accretion flow or as the result of jet precession. The total kinetic energy of the ejecta that we infer of ˜ few 1053 erg requires a highly efficient jet launching mechanism. Our jet model providing the best fit to the light curve of the on-axis event Swift J1644+57 is used to predict the radio light curves for off-axis viewing angles. Implications for the presence of relativistic jets from tidal disruption events (TDEs) detected via their thermal disc emission, as well as the prospects for detecting orphan TDE afterglows with upcoming wide-field radio surveys and resolving the jet structure with long baseline interferometry, are discussed.

  13. DYNAMICS AND AFTERGLOW LIGHT CURVES OF GAMMA-RAY BURST BLAST WAVES WITH A LONG-LIVED REVERSE SHOCK

    SciTech Connect

    Uhm, Z. Lucas; Zhang Bing; Hascoeet, Romain; Daigne, Frederic; Mochkovitch, Robert; Park, Il H.

    2012-12-20

    We perform a detailed study on the dynamics of a relativistic blast wave with the presence of a long-lived reverse shock (RS). Although a short-lived RS has been widely considered, the RS is believed to be long-lived as a consequence of a stratification expected on the ejecta Lorentz factors. The existence of a long-lived RS causes the forward shock (FS) dynamics to deviate from a self-similar Blandford-McKee solution. Employing the ''mechanical model'' that correctly incorporates the energy conservation, we present an accurate solution for both the FS and RS dynamics. We conduct a sophisticated calculation of the afterglow emission. Adopting a Lagrangian description of the blast wave, we keep track of an adiabatic evolution of numerous shells between the FS and RS. An evolution of the electron spectrum is also followed individually for every shell. We then find the FS and RS light curves by integrating over the entire FS and RS shocked regions, respectively. Exploring a total of 20 different ejecta stratifications, we explain in detail how a stratified ejecta affects its blast wave dynamics and afterglow light curves. We show that, while the FS light curves are not sensitive to the ejecta stratifications, the RS light curves exhibit much richer features, including steep declines, plateaus, bumps, re-brightenings, and a variety of temporal decay indices. These distinctive RS features may be observable if the RS has higher values of the microphysics parameters than the FS. We discuss possible applications of our results in understanding the gamma-ray burst afterglow data.

  14. Dynamics and Afterglow Light Curves of Gamma-Ray Burst Blast Waves with a Long-lived Reverse Shock

    NASA Astrophysics Data System (ADS)

    Uhm, Z. Lucas; Zhang, Bing; Hascoët, Romain; Daigne, Frédéric; Mochkovitch, Robert; Park, Il H.

    2012-12-01

    We perform a detailed study on the dynamics of a relativistic blast wave with the presence of a long-lived reverse shock (RS). Although a short-lived RS has been widely considered, the RS is believed to be long-lived as a consequence of a stratification expected on the ejecta Lorentz factors. The existence of a long-lived RS causes the forward shock (FS) dynamics to deviate from a self-similar Blandford-McKee solution. Employing the "mechanical model" that correctly incorporates the energy conservation, we present an accurate solution for both the FS and RS dynamics. We conduct a sophisticated calculation of the afterglow emission. Adopting a Lagrangian description of the blast wave, we keep track of an adiabatic evolution of numerous shells between the FS and RS. An evolution of the electron spectrum is also followed individually for every shell. We then find the FS and RS light curves by integrating over the entire FS and RS shocked regions, respectively. Exploring a total of 20 different ejecta stratifications, we explain in detail how a stratified ejecta affects its blast wave dynamics and afterglow light curves. We show that, while the FS light curves are not sensitive to the ejecta stratifications, the RS light curves exhibit much richer features, including steep declines, plateaus, bumps, re-brightenings, and a variety of temporal decay indices. These distinctive RS features may be observable if the RS has higher values of the microphysics parameters than the FS. We discuss possible applications of our results in understanding the gamma-ray burst afterglow data.

  15. The Energy Budget of GRBs Based on a Large Sample of Prompt and Afterglow Observations

    NASA Astrophysics Data System (ADS)

    Wygoda, N.; Guetta, D.; Mandich, M. A.; Waxman, E.

    2016-06-01

    We compare the isotropic equivalent 15-2000 keV γ-ray energy, E γ , emitted by a sample of 91 swift Gamma-Ray Bursts with known redshifts, with the isotropic equivalent fireball energy, E fb, as estimated within the fireball model framework from X-ray afterglow observations of these bursts. The uncertainty in E γ , which spans the range of ˜1051 to ˜1053.5 erg, is ≈25% on average, due mainly to the extrapolation from the BAT detector band to the 15-2000 keV band. The uncertainty in E fb is approximately a factor of 2, due mainly to the X-ray measurements’ scatter. We find E γ and E fb to be tightly correlated. The average(std) of {η }γ 11 {hr}\\equiv {{log}}10({E}γ /(3{\\varepsilon }{{e}}{E}{{fb}}11 {hr})) are -0.34(0.60), and the upper limit on the intrinsic spread of η γ is approximately 0.5 ({\\varepsilon }{{e}} is the fraction of energy carried by electrons and {E}{{fb}}x {hr} is inferred from the X-ray flux at x hours). {E}{{fb}}3 {hr} and {E}{{fb}}11 {hr} are similar, with an average(std) of {{log}}10({E}{{fb}}3 {hr}/{E}{{fb}}11 {hr}) of 0.04(0.28). The small variance of η γ implies that burst-to-burst variations in {\\varepsilon }{{e}} and in the efficiency of fireball energy conversion to γ-rays are small, and suggests that both are of order unity. The small variance of η γ and the similarity of {E}{{fb}}3 {hr} and {E}{{fb}}11 {hr} further imply that deviations from a simple fireball model description, if present, are small. This puts stringent constraints on models incorporating such modifications (due e.g., to radiative losses, energy injection, off-axis viewing).

  16. Study of GRB Light-curve Decay Indices in the Afterglow Phase

    NASA Astrophysics Data System (ADS)

    Del Vecchio, Roberta; Dainotti, Maria Giovanna; Ostrowski, Michał

    2016-09-01

    In this work, we study the distribution of temporal power-law decay indices, α, in the gamma-ray burst (GRB) afterglow phase, fitted for 176 GRBs (139 long GRBs, 12 short GRBs with extended emission, and 25 X-ray flashes) with known redshifts. These indices are compared with the temporal decay index, α W , derived with the light-curve fitting using the Willingale et al. model. This model fitting yields similar distributions of α W to the fitted α, but for individual bursts a difference can be significant. Analysis of (α, L a ) distribution, where L a is the characteristic luminosity at the end of the plateau, reveals only a weak correlation of these quantities. However, we discovered a significant regular trend when studying GRB α values along the Dainotti et al. correlation between L a and the end time of the plateau emission in the rest frame, {T}a* , hereafter LT correlation. We note a systematic variation of the α parameter distribution with luminosity for any selected {T}a* . We analyze this systematics with respect to the fitted LT correlation line, expecting that the presented trend may allow us to constrain the GRB physical models. We also attempted to use the derived correlation of α ({T}a) versus {L}a({T}a) to diminish the luminosity scatter related to the variations of α along the LT distribution, a step forward in the effort of standardizing GRBs. A proposed toy model accounting for this systematics applied to the analyzed GRB distribution results in a slight increase of the LT correlation coefficient.

  17. Kinetics of positive ions and electrically neutral active particles in afterglow in neon at low pressure

    SciTech Connect

    Pejović, Milić M. Nešić, Nikola T.; Pejović, Momčilo M.

    2014-04-15

    Kinetics of positive ions and electrically neutral active particles formed during breakdown and successive discharge in neon-filled tube at 6.6 millibars pressure had been analyzed. This analysis was performed on the basis of mean value of electrical breakdown time delay t{sup ¯}{sub d} dependence on afterglow period τ (memory curve). It was shown that positive ions are present in the 1μs < τ < 30 ms interval, which is manifested through t{sup ¯}{sub d} slow increase with the increase of τ. A rapid t{sup ¯}{sub d} increase in the 30 ms < τ < 3 s interval is a consequence of significant decrease of positive ions concentration and dominant role in breakdown initiation have ground state nitrogen atoms, which further release secondary electrons from the cathode by catalytic recombination process. These atoms are formed during discharge by dissociation of ground state nitrogen molecules that are present as impurities in neon. For τ > 3 s, breakdown is initiated by cosmic rays and natural radioactivity. The increase of discharge current leads to decrease of t{sup ¯}{sub d} due to the increase of positive ions concentration in inter electrode gap. The increase of applied voltage also decreases t{sup ¯}{sub d} for τ > 30 ms due to the increase of the probability for initial electron to initiate breakdown. The presence of UV radiation leads to the decrease of t{sup ¯}{sub d} due to the increased electron yield caused by photoelectrons. The influence of photoelectrons on breakdown initiation can be noticed for τ > 0.1 ms, while they dominantly determine t{sup ¯}{sub d} for τ > 30 ms.

  18. A coordinated flowing afterglow and crossed beam study of electron attachment to CCl3Br

    NASA Astrophysics Data System (ADS)

    Spanel, P.; Smith, D.; Matejcik, S.; Kiendler, A.; Mark, T. D.

    1997-11-01

    Dissociative electron attachment to CCl3Br has been studied using a flowing afterglow/Langmuir probe (FALP) and a crossed beam technique. In the FALP experiment the overall attachment rate coefficients and the branching ratio into the Cl- and the Br- product channels, R = Cl-/(Cl- + Br-), were measured as a function of the gas temperature, Tg, in the range of 300-540K and the electron temperatures, Te, from Tg to 4000K indicating that R approached the statistical value of 0.75 at the highest Tg. At Tg = 540K both Cl2-1 and ClBr- molecular ions were observed at about the 2% level. An apparent activation energy of 55 meV for the overall attachment reaction was derived using a model developed previously to describe the dependence of dissociative electron attachment rates on Tg and Te. The crossed beam experiment provided relative attachment cross-sections for the production of Cl- and Br- as a function of electron energy, E, from near zero up to ~2 eV at several Tg within the range 311-423 K. The absolute cross-sections at Tg = 311K were obtained from the FALP value using a calibration procedure. At low E the overall attachment cross-section varies as E-1 in accordance with s-wave capture theory. In accordance with the FALP data R increases from 0.2 at low E and the lowest Tg to the statistical value of 0.75 at high E and high Tg. A peak observed in the cross-section at an E of about 0.7 eV is tentatively attributed to p-wave electron attachment. The rapid decrease of this peak cross-section with Tg is ascribed to autodetachment.

  19. GRB 080503 LATE AFTERGLOW RE-BRIGHTENING: SIGNATURE OF A MAGNETAR-POWERED MERGER-NOVA

    SciTech Connect

    Gao, He; Ding, Xuan; Wu, Xue-Feng; Dai, Zi-Gao; Zhang, Bing E-mail: xfwu@pmo.ac.cn E-mail: zhang@physics.unlv.edu

    2015-07-10

    GRB 080503 is a short gamma-ray burst (GRB) detected by Swift and has been classified as a GRB originating from a compact star merger. The soft extended emission and the simultaneous late re-brightening in both the X-ray and optical afterglow light curves raise interesting questions regarding its physical origin. We show that the broadband data of GRB 080503 can be well explained within the framework of the double neutron star merger model, provided that the merger remnant is a rapidly rotating massive neutron star with an extremely high magnetic field (i.e., a millisecond magnetar). We show that the late optical re-brightening is consistent with the emission from a magnetar-powered “merger-nova.” This adds one more case to the growing sample of merger-novae associated with short GRBs. The soft extended emission and the late X-ray excess emission are well connected through a magnetar dipole spin-down luminosity evolution function, suggesting that direct magnetic dissipation is the mechanism to produce these X-rays. The X-ray emission initially leaks from a hole in the merger ejecta pierced by the short GRB jet. The hole subsequently closes after the magnetar spins down and the magnetic pressure drops below ram pressure. The X-ray photons are then trapped behind the merger-nova ejecta until the ejecta becomes optically thin at a later time. This explains the essentially simultaneous re-brightening in both the optical and X-ray light curves. Within this model, future gravitational-wave sources could be associated with a bright X-ray counterpart along with the merger-nova, even if the short GRB jet beams away from Earth.

  20. Radio afterglow of the jetted tidal disruption event Swift J1644+57

    NASA Astrophysics Data System (ADS)

    Metzger, B. D.; Giannios, D.; Mimica, P.

    2012-12-01

    The recent transient event Swift J1644+57 has been interpreted as resulting from a relativistic outflow, powered by the accretion of a tidally disrupted star onto a supermassive black hole. This discovery of a new class of relativistic transients opens new windows into the study of tidal disruption events (TDEs) and offers a unique probe of the physics of relativistic jet formation and the conditions in the centers of distant quiescent galaxies. Unlike the rapidly-varying γ/X-ray emission from Swift J1644+57, the radio emission varies more slowly and is well modeled as synchrotron radiation from the shock interaction between the jet and the gaseous circumnuclear medium (CNM). Early after the onset of the jet, a reverse shock propagates through and decelerates the ejecta released during the first few days of activity, while at much later times the outflow approaches the self-similar evolution of Blandford and McKee. The point at which the reverse shock entirely crosses the earliest ejecta is clearly observed as an achromatic break in the radio light curve at t ≈ 10 days. The flux and break frequencies of the afterglow constrain the properties of the jet and the CNM, including providing robust evidence for a narrowly collimated jet. I briefly discuss the implications of Swift J1644+57 for the fraction of TDEs accompanied by relativistic jets; the physics of jet formation more broadly; and the prospects for detecting off-axis TDE radio emission, either via follow-up observations of TDE candidates discovered at other wavelengths or blindly with upcoming wide-field radio surveys. The radio rebrightening observed months after the onset of the jet remains a major unsolved mystery, the resolution of which may require considering a jet with more complex (temporal or angular) structure.

  1. DISCOVERY AND REDSHIFT OF AN OPTICAL AFTERGLOW IN 71 deg{sup 2}: iPTF13bxl AND GRB 130702A

    SciTech Connect

    Singer, Leo P.; Brown, Duncan A.; Bradley Cenko, S.; Gehrels, Neil; McEnery, Julie; Kasliwal, Mansi M.; Mulchaey, John; Perley, Daniel A.; Kulkarni, S. R.; Bellm, Eric; Barlow, Tom; Cao, Yi; Horesh, Assaf; Ofek, Eran O.; Arcavi, Iair; Nugent, Peter E.; Bloom, Joshua S.; Corsi, Alessandra; Frail, Dale A.; Masci, Frank J.; and others

    2013-10-20

    We report the discovery of the optical afterglow of the γ-ray burst (GRB) 130702A, identified upon searching 71 deg{sup 2} surrounding the Fermi Gamma-ray Burst Monitor (GBM) localization. Discovered and characterized by the intermediate Palomar Transient Factory, iPTF13bxl is the first afterglow discovered solely based on a GBM localization. Real-time image subtraction, machine learning, human vetting, and rapid response multi-wavelength follow-up enabled us to quickly narrow a list of 27,004 optical transient candidates to a single afterglow-like source. Detection of a new, fading X-ray source by Swift and a radio counterpart by CARMA and the Very Large Array confirmed the association between iPTF13bxl and GRB 130702A. Spectroscopy with the Magellan and Palomar 200 inch telescopes showed the afterglow to be at a redshift of z = 0.145, placing GRB 130702A among the lowest redshift GRBs detected to date. The prompt γ-ray energy release and afterglow luminosity are intermediate between typical cosmological GRBs and nearby sub-luminous events such as GRB 980425 and GRB 060218. The bright afterglow and emerging supernova offer an opportunity for extensive panchromatic follow-up. Our discovery of iPTF13bxl demonstrates the first observational proof-of-principle for ∼10 Fermi-iPTF localizations annually. Furthermore, it represents an important step toward overcoming the challenges inherent in uncovering faint optical counterparts to comparably localized gravitational wave events in the Advanced LIGO and Virgo era.

  2. A Decade of Short-duration Gamma-Ray Burst Broadband Afterglows: Energetics, Circumburst Densities, and Jet Opening Angles

    NASA Astrophysics Data System (ADS)

    Fong, W.; Berger, E.; Margutti, R.; Zauderer, B. A.

    2015-12-01

    We present a comprehensive catalog and analysis of broadband afterglow observations for 103 short-duration gamma-ray bursts (GRBs), comprised of all short GRBs from 2004 November to 2015 March with prompt follow-up observations in the X-ray, optical, near-infrared (NIR), and/or radio bands. These afterglow observations have uncovered 71 X-ray detections, 30 optical/NIR detections, and 4 radio detections. Employing the standard afterglow synchrotron model, we perform joint probability analyses for a subset of 38 short GRBs with well-sampled light curves to infer the burst isotropic-equivalent energies and circumburst densities. For this subset, we find median isotropic-equivalent γ-ray and kinetic energies of Eγ,iso ≈ 2 × 1051 erg, and EK,iso ≈ (1-3) × 1051 erg, respectively, depending on the values of the model input parameters. We further find that short GRBs occur in low-density environments, with a median density of n ≈ (3-15) × 10-3 cm-3, and that ≈80%-95% of bursts have densities of n ≲ 1 cm-3. We investigate trends between the circumburst densities and host galaxy properties, and find that events located at large projected offsets of ≳10 effective radii from their hosts exhibit particularly low densities of n ≲ 10-4 cm-3, consistent with an intergalactic medium-like environment. Using late-time afterglow data for 11 events, we find a median jet opening angle of θj = 16 ± 10°. We also calculate a median beaming factor of fb ≈ 0.04, leading to a beaming-corrected total energy release of Etrue ≈ 1.6 × 1050 erg. Furthermore, we calculate a beaming-corrected event rate of {{R}}{{true}}={270}-180+1580 Gpc-3 yr-1, or ≈ {8}-5+47 yr-1 within a 200 Mpc volume, the Advanced LIGO/Virgo typical detection distance for NS-NS binaries.

  3. A COMPREHENSIVE STUDY OF GAMMA-RAY BURST OPTICAL EMISSION. III. BRIGHTNESS DISTRIBUTIONS AND LUMINOSITY FUNCTIONS OF OPTICAL AFTERGLOWS

    SciTech Connect

    Wang Xianggao; Liang Enwei; Li Liang; Lu Ruijing; Wei Jianyan; Zhang Bing

    2013-09-10

    We continue our systematic statistical study on optical afterglow data of gamma-ray bursts (GRBs). We present the apparent magnitude distributions of early optical afterglows at different epochs (t = 10{sup 2} s, 10{sup 3} s, and 1 hr) for the optical light curves of a sample of 93 GRBs (the global sample) and for sub-samples with an afterglow onset bump or a shallow decay segment. For the onset sample and shallow decay sample we also present the brightness distribution at the peak time t{sub p} and break time t{sub b}, respectively. All the distributions can be fit with Gaussian functions. We further perform Monte Carlo simulations to infer the luminosity function of GRB optical emission at the rest-frame time 10{sup 3} s, t{sub p}, and t{sub b}. Our results show that a single power-law luminosity function is adequate to model the data with indices -1.40 {+-} 0.10, -1.06 {+-} 0.16, and -1.54 {+-} 0.22. Based on the derived rest-frame 10{sup 3} s luminosity function, we generate the intrinsic distribution of the R-band apparent magnitude M{sub R} at the observed time 10{sup 3} s post-trigger, which peaks at M{sub R} = 22.5 mag. The fraction of GRBs whose R-band magnitude is fainter than 22 mag and 25 mag and at the observer time 10{sup 3} s are {approx}63% and {approx}25%, respectively. The detection probabilities of the optical afterglows with ground-based robotic telescopes and the UV-Optical Telescope on board Swift are roughly consistent with that inferred from this intrinsic M{sub R} distribution, indicating that the variations of the dark GRB fraction among the samples with different telescopes may be due to the observational selection effect, although the existence of an intrinsically dark GRB population cannot be ruled out.

  4. Transition from interpulse to afterglow plasmas driven by repetitive short-pulse microwaves in a multicusp magnetic field

    SciTech Connect

    Pandey, Shail; Sahu, Debaprasad; Bhattacharjee, Sudeep

    2012-08-15

    In the power-off phase, plasmas generated by repetitive short-pulse microwaves in a multicusp magnetic field show a transitive nature from interpulse to afterglow as a function of pulse duration t{sub w} = 20-200 {mu}s. The ionized medium can be driven from a highly non equilibrium to an equilibrium state inside the pulses, thereby dictating the behavior of the plasma in the power-off phase. Compared to afterglows, interpulse plasmas observed for t{sub w} < 50 {mu}s are characterized by a quasi-steady-state in electron density that persists for {approx} 20-40 {mu}s even after the end of the pulse and has a relatively slower decay rate ({approx} 4.3 Multiplication-Sign 10{sup 4} s{sup -1}) of the electron temperature, as corroborated by optical measurements. The associated electron energy probability function indicates depletion in low energy electrons which appear at higher energies just after the end of the pulse. The transition occurs at t{sub w} {approx} 50 {mu}s as confirmed by time evolution of integrated electron numbers densities obtained from the distribution function.

  5. Gamma-Ray Burst Afterglows as Probes of Environment and Blastwave Physics. 1; Absorption by Host Galaxy Gas and Dust

    NASA Technical Reports Server (NTRS)

    Starling, R. L. C.; Wijers, R. A. M. J.; Wiersema, K.; Rol, E.; Curran, P. A.; Kouveliotou, C.; vanderHorst, A. J.; Heemskerk, M. H. M.

    2006-01-01

    We use a new approach to obtain limits on the absorbing columns towards an initial sample of 10 long Gamma-Ray Bursts observed with BeppoSAX and selected on the basis of their good optical and nIR coverage, from simultaneous fits to nIR, optical and X-ray afterglow data, in count space and including the effects of metallicity. In no cases is a MIV-like ext,inction preferred, when testing MW, LMC and SMC extinction laws. The 2175A bump would in principle be detectable in all these afterglows, but is not present in the data. An SMC-like gas-to-dust ratio or lower value can be ruled out for 4 of the hosts analysed here (assuming Sh4C metallicity and extinction law) whilst the remainder of the sample have too large an error to discriminate. We provide a more accurate estimate of the line-of-sight extinction and improve upon the uncertainties for the majority of the extinction measurements made in previous studies of this sample. We discuss this method to determine extinction values in comparison with the most commonly employed existing methods.

  6. Electron ranaway and ion-ion plasma formation in afterglow low-pressure plasma of oxygen-containing gas mixtures

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, Anatoly; Bogdanov, Eugene; Kosykh, Nikolay; Gutsev, Sergey

    2012-10-01

    Experimental investigation of temporal evolution of charged plasma species in afterglow plasma of oxygen-containing mixtures have been investigated. The probe VAC and the time dependence of the saturation positive and negative particles currents to a probe in a fixed bias voltage were performed. The decay of afterglow low-pressure electronegative gas plasmas take place in two distinct stages (the electron-ion stage, and the ion-ion stage) as it was shown in [1] for pure oxygen. In the first stage, the negative ions are locked within a discharge volume and plasma is depleted of electrons and positive ions. The electron density decay is faster, than exponential, and practically all electrons leave plasma volume during finite time followed by the ion--ion (electron-free) plasma formation. The decay of the ion-ion plasma depends on the presence of detachment. With a large content of electronegative gas (oxygen) in a mixture, when there is a ``detachment particles,'' a small fraction of the electrons appearing as a result of the detachment continue to hold all negative ions in the discharge volume. In this case, the densities of all charged plasma components decay according to the same exponential law with a characteristic detachment time. At a low oxygen content in the gas mixture there is no detachment and plasma decays by an ion--ion ambipolar diffusion mechanism.[4pt][1]. S.A.Gutsev, A.A.Kudryavtsev, V.A.Romanenko. Tech.Phys. 40, 1131, (1995).

  7. Use of Interrupted Helium Flow in the Analysis of Vapor Samples with Flowing Atmospheric-Pressure Afterglow-Mass Spectrometry.

    PubMed

    Storey, Andrew P; Zeiri, Offer M; Ray, Steven J; Hieftje, Gary M

    2017-02-01

    The flowing atmospheric-pressure afterglow (FAPA) source was used for the mass-spectrometric analysis of vapor samples introduced between the source and mass spectrometer inlet. Through interrupted operation of the plasma-supporting helium flow, helium consumption is greatly reduced and dynamic gas behavior occurs that was characterized by schlieren imaging. Moreover, mass spectra acquired immediately after the onset of helium flow exhibit a signal spike before declining and ultimately reaching a steady level. This initial signal appears to be due to greater interaction of sample vapor with the afterglow of the source when helium flow resumes. In part, the initial spike in signal can be attributed to a pooling of analyte vapor in the absence of helium flow from the source. Time-resolved schlieren imaging of the helium flow during on and off cycles provided insight into gas-flow patterns between the FAPA source and the MS inlet that were correlated with mass-spectral data. Graphical Abstract ᅟ.

  8. Afterglow emission in gamma-ray bursts - I. Pair-enriched ambient medium and radiative blast waves

    NASA Astrophysics Data System (ADS)

    Nava, L.; Sironi, L.; Ghisellini, G.; Celotti, A.; Ghirlanda, G.

    2013-08-01

    Forward shocks caused by the interaction between a relativistic blast wave and the circumburst medium are thought to be responsible for the afterglow emission in gamma-ray bursts (GRBs). We consider the hydrodynamics of a spherical relativistic blast wave expanding into the surrounding medium and we generalize the standard theory in order to account for several effects that are generally ignored. In particular, we consider the role of adiabatic and radiative losses in the hydrodynamical evolution of the shock, under the assumption that the cooling losses are fast. Our model can describe adiabatic, fully radiative and semiradiative blast waves, and can describe the effects of a time-varying radiative efficiency. The equations we present are valid for arbitrary density profiles, and also for a circumburst medium enriched with electron-positron pairs. The presence of pairs enhances the fraction of shock energy gained by the leptons, thus increasing the importance of radiative losses. Our model allows us to study whether the high-energy (>0.1 GeV) emission in GRBs may originate from afterglow radiation. In particular, it is suitable to test whether the fast decay of the high-energy light curve observed in several Fermi Large Area Telescope GRBs can be ascribed to an initial radiative phase, followed by the standard adiabatic evolution.

  9. Dynamics and afterglow light curves of gamma-ray burst blast waves encountering a density bump or void

    SciTech Connect

    Uhm, Z. Lucas; Zhang, Bing E-mail: zhang@physics.unlv.edu

    2014-07-01

    We investigate the dynamics and afterglow light curves of gamma-ray burst blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the characteristic response features that each type of density structure in the medium leaves on the forward shock (FS) and reverse shock (RS) dynamics for blast waves with either a long-lived or short-lived RS. We show that when the ambient medium density drops, the blast waves exhibit in some cases a period of an actual acceleration (even during their deceleration stage) due to adiabatic cooling of blast waves. Comparing numerical examples that have different shapes of bumps or voids, we propose a number of consistency tests that must be satisfied by correct modeling of blast waves. Our model results successfully pass these tests. Employing a Lagrangian description of blast waves, we perform a sophisticated calculation of afterglow emission. We show that as a response to density structures in the ambient medium, the RS light curves produce more significant variations than the FS light curves. Some observed features (such as rebrightenings, dips, or slow wiggles) can be more easily explained within the RS model. We also discuss the origin of these different features imprinted on the FS and RS light curves.

  10. A study of gamma ray bursts with afterglow plateau phases associated with supernovae

    NASA Astrophysics Data System (ADS)

    Dainotti, M. G.; Nagataki, S.; Maeda, K.; Postnikov, S.; Pian, E.

    2017-04-01

    Context. The analysis of 176 gamma ray burst (GRB) afterglow plateaus observed by Swift from GRBs with known redshifts revealed that the subsample of long GRBs associated with supernovae (LONG-SNe), comprising 19 events, presents a very high correlation coefficient between the luminosity at the end of the plateau phase LX(Ta) = La and the end time of the plateau . Furthermore, these SNe Ib/c associated with GRBs also obey the peak-magnitude stretch relation, which is similar to that used to standardize the SNe Ia. Aims: Our aim is to investigate a category of GRBs with plateau and associated with SNe to compare our correlation for this sample with the correlation for long GRBs for which no associated SN has been observed (hereafter LONG-NO-SNe, 128 GRBs) and to check whether there is a difference among these subsamples. Methods: We first adopted a nonparametric statistical method to take redshift evolution into account and to check if and how this effect may steepen the slope for the LONG-NO-SNe sample. This procedure is necessary because this sample is observed at much higher redshift than the GRB-SNe sample. Therefore, removing selection bias is the first step before any comparison among samples observed at different redshifts could be properly performed. Then, we applied the T-student test to evaluate a statistical difference between the slopes of the two samples. Results: We demonstrate that there is no evolution for the slope of the LONG-NO-SNe sample and no evolution is expected for GRBs observed at small redshifts such as those present in the LONG-SNe sample. The difference between the slope of the LONG-NO-SNe and the slope of LONG-SNe, i.e., those with firm spectral detection of SN components, is statistically significant (P = 0.005). Conclusions: This possibly suggests that, unlike LONG-NO-SNe, LONG-SNe with firm spectroscopic features of the associated SNe might not require a standard energy reservoir in the plateau phase. Therefore, this analysis may

  11. THE NEEDLE IN THE 100 deg{sup 2} HAYSTACK: UNCOVERING AFTERGLOWS OF FERMI GRBs WITH THE PALOMAR TRANSIENT FACTORY

    SciTech Connect

    Singer, Leo P.; Kasliwal, Mansi M.; Cenko, S. Bradley; Cucchiara, Antonino; Gehrels, Neil; Perley, Daniel A.; Cao, Yi; Anderson, Gemma E.; Fender, Rob P.; Anupama, G. C.; Arcavi, Iair; Bhalerao, Varun; Bue, Brian D.; Connaughton, Valerie; Corsi, Alessandra; Fox, Derek B.; Goldstein, Adam; Gorosabel, J.; and others

    2015-06-10

    The Fermi Gamma-ray Space Telescope has greatly expanded the number and energy window of observations of gamma-ray bursts (GRBs). However, the coarse localizations of tens to a hundred square degrees provided by the Fermi GRB Monitor instrument have posed a formidable obstacle to locating the bursts’ host galaxies, measuring their redshifts, and tracking their panchromatic afterglows. We have built a target-of-opportunity mode for the intermediate Palomar Transient Factory in order to perform targeted searches for Fermi afterglows. Here, we present the results of one year of this program: 8 afterglow discoveries out of 35 searches. Two of the bursts with detected afterglows (GRBs 130702A and 140606B) were at low redshift (z = 0.145 and 0.384, respectively) and had spectroscopically confirmed broad-line Type Ic supernovae. We present our broadband follow-up including spectroscopy as well as X-ray, UV, optical, millimeter, and radio observations. We study possible selection effects in the context of the total Fermi and Swift GRB samples. We identify one new outlier on the Amati relation. We find that two bursts are consistent with a mildly relativistic shock breaking out from the progenitor star rather than the ultra-relativistic internal shock mechanism that powers standard cosmological bursts. Finally, in the context of the Zwicky Transient Facility, we discuss how we will continue to expand this effort to find optical counterparts of binary neutron star mergers that may soon be detected by Advanced LIGO and Virgo.

  12. Tuning the afterglow plasma composition in Ar/N2/O2 mixtures: characteristics of a flowing surface-wave microwave discharge system

    NASA Astrophysics Data System (ADS)

    Kutasi, Kinga; Noël, Cédric; Belmonte, Thierry; Guerra, Vasco

    2016-10-01

    A self-consistent kinetic model is used to study the possibility of tuning the plasma composition in the afterglow of a flowing surface-wave microwave discharge by the different discharge and system parameters in the case of 90%Ar-10%(N2-O2) and N2-O2 mixtures. The afterglow system consists of a 0.5 cm diameter quartz tube of 50 cm in length—where the discharge is generated and the early-afterglow develops—and an afterglow reactor. The plasma composition is studied at the end of the discharge plasma column and at the reactor inlet as a function of the N2:O2 ratio for selected conditions, which are set with the system parameters and are illustrated in the experimental set-up. The validity of the model used is proven by the agreement of the calculated atomic densities with those measured by mass spectrometry. Due to the pressure drop along the tube, the position of the discharge (which also defines the lengths of the early-afterglow, t aft) and the discharge pressure (p dis) can be set with the position of the wave coupler—surfatron—along the tube at a constant gas flow rate (which defines the pressure in the reactor, p reac). It is shown that the relative densities of species at the end of plasma column, which constitute the initial condition for the afterglow, depend on the discharge pressure. Therefore, at a constant gas flow rate with the position of the surfatron the plasma composition in the reactor is changing due to the variation of both the p dis and t aft. The evolution of the plasma composition is also studied when both the surfatron’s position and the gas flow rate are changed, realizing conditions (i) with the same p dis, and different t aft and p reac, and (ii) with the same t aft, and different p dis and p reac. Comparing the N2-O2 binary and the ternary mixtures, it is shown that the atomic densities obtained in the binary mixtures can be reproduced in ternary mixtures with different N2:O2 ratios. Furthermore, according to the spectra

  13. A complete sample of bright Swift Gamma-ray bursts: X-ray afterglow luminosity and its correlation with the prompt emission

    NASA Astrophysics Data System (ADS)

    D'Avanzo, P.; Salvaterra, R.; Sbarufatti, B.; Nava, L.; Melandri, A.; Bernardini, M. G.; Campana, S.; Covino, S.; Fugazza, D.; Ghirlanda, G.; Ghisellini, G.; Parola, V. La; Perri, M.; Vergani, S. D.; Tagliaferri, G.

    2012-09-01

    We investigate whether there is any correlation between the X-ray afterglow luminosity and the prompt emission properties of a carefully selected sub-sample of bright Swift long Gamma-ray bursts (GRBs) nearly complete in redshift (˜90 per cent). Being free of selection effects (except flux limit), this sample provides the possibility to compare the rest frame physical properties of GRB prompt and afterglow emission in an unbiased way. The afterglow X-ray luminosities are computed at four different rest frame times (5 min, 1 h, 11 h and 24 h after trigger) and compared with the prompt emission isotropic energy Eiso, the isotropic peak luminosity Liso and the rest frame peak energy Epeak. We find that the rest frame afterglow X-ray luminosity do correlate with these prompt emission quantities, but the significance of each correlation decreases over time. This result is in agreement with the idea that the GRB X-ray light curve can be described as the result of a combination of different components whose relative contribution and weight change with time, with the prompt and afterglow emission dominating at early and late time, respectively. In particular, we found evidence that the plateau and the shallow decay phase often observed in GRB X-ray light curves are powered by activity from the central engine. The existence of the LX - Eiso correlation at late times (trf≥11h) suggests a similar radiative efficiency among different bursts with on average about 6 per cent of the total kinetic energy powering the prompt emission.

  14. HELIUM IN NATAL H II REGIONS: THE ORIGIN OF THE X-RAY ABSORPTION IN GAMMA-RAY BURST AFTERGLOWS

    SciTech Connect

    Watson, Darach; Andersen, Anja C.; Fynbo, Johan P. U.; Hjorth, Jens; Kruehler, Thomas; Laursen, Peter; Leloudas, Giorgos; Malesani, Daniele; Zafar, Tayyaba; Gorosabel, Javier

    2013-05-01

    Soft X-ray absorption in excess of Galactic is observed in the afterglows of most gamma-ray bursts (GRBs), but the correct solution to its origin has not been arrived at after more than a decade of work, preventing its use as a powerful diagnostic tool. We resolve this long-standing problem and find that absorption by He in the GRB's host H II region is responsible for most of the absorption. We show that the X-ray absorbing column density (N{sub H{sub X}}) is correlated with both the neutral gas column density and with the optical afterglow's dust extinction (A{sub V} ). This correlation explains the connection between dark bursts and bursts with high N{sub H{sub X}} values. From these correlations, we exclude an origin of the X-ray absorption which is not related to the host galaxy, i.e., the intergalactic medium or intervening absorbers are not responsible. We find that the correlation with the dust column has a strong redshift evolution, whereas the correlation with the neutral gas does not. From this, we conclude that the column density of the X-ray absorption is correlated with the total gas column density in the host galaxy rather than the metal column density, in spite of the fact that X-ray absorption is typically dominated by metals. The strong redshift evolution of N{sub H{sub X}}/A{sub V} is thus a reflection of the cosmic metallicity evolution of star-forming galaxies and we find it to be consistent with measurements of the redshift evolution of metallicities for GRB host galaxies. We conclude that the absorption of X-rays in GRB afterglows is caused by He in the H II region hosting the GRB. While dust is destroyed and metals are stripped of all of their electrons by the GRB to great distances, the abundance of He saturates the He-ionizing UV continuum much closer to the GRB, allowing it to remain in the neutral or singly-ionized state. Helium X-ray absorption explains the correlation with total gas, the lack of strong evolution with redshift, as well

  15. On the afterglow and host galaxy of GRB 021004: A comprehensivestudy with the Hubble Space Telescope1

    SciTech Connect

    Fynbo, J.P.U.; Gorosabel, J.; Smette, A.; Fruchter, A.; Hjorth,J.; Pedersen, K.; Levan, A.; Burud, I.; Sahu, K.; Vreeswijk, P.M.; Bergeron, E.; Kouveliotou1, C.; Tanvir, N.; Thorsett11, S.E.; Wijers,R.A.M.J.; Castro Ceron, J.M.; Castro-Tirado, A.; Garnavich, P.; Holland,S.T.; Jakobsson, P.; Moller, P.; Nugent, P.; Pian, E.; Rhoads, J.; Thomsen, B.; Watson, D.; Woosley, S.

    2004-12-01

    We report on Hubble Space Telescope (HST) observations of the late-time afterglow and host galaxy of GRB 021004 (z = 2.33).Although this gamma-ray burst (GRB) is one of the best observed so far in terms of sampling in the time domain, multi-wavelength coverage and polarimetric observations, there is large disagreement between different measurements and interpretations of this burst in the literature. We have observed the field of GRB 021004 with the HST at multiple epochs from 3 days until almost 10 months after the burst. With STI S prism and G430L spectroscopy we cover the spectral region from about 2000 Angstrom to 5700 Angstrom corresponding to 600 1700 Angstrom in the rest frame. From the limit on the flux recovery bluewards of the Lyman-limit we constrain the H I column density to be above 1 x 1018 cm-2 (5 sigma). Based on ACS and N ICMOS imaging we find that the afterglow evolved a chromatically within the errors (any variation must be less then 5 percent) during the period of HST observations. The color changes observed by other authors during the first four days must be related to a 'noisy' phenomenon superimposed on an afterglow component with a constant spectral shape. This also means that the cooling break has remained on the blue side of the optical part of the spectrum for at least two weeks after the explosion. The optical to X-ray slope OX is consistent with being the same at 1.4 and 52.4 days after the burst. This indicates that the cooling frequency is constant and hence, according to fireball models, that the circumburst medium has a constant density profile. The late-time slope of the light curve (alpha 2, F nu proportional to t-alpha2) is in the range 2 = 1.8-1.9, although inconsistent with a single power-law. This could be due to a late-time flattening caused by the transition to non-relativistic expansion or due to excess emission (a 'bump' in the light curve) about 7 days afterburst. The host galaxy is like most previously studied GRB hosts

  16. AFTERGLOW OBSERVATIONS OF FERMI LARGE AREA TELESCOPE GAMMA-RAY BURSTS AND THE EMERGING CLASS OF HYPER-ENERGETIC EVENTS

    SciTech Connect

    Cenko, S. B.; Butler, N. R.; Cobb, B. E.; Cucchiara, A.; Bloom, J. S.; Perley, D. A.; Filippenko, A. V.; Frail, D. A.; Harrison, F. A.; Haislip, J. B.; Reichart, D. E.; Ivarsen, K. M.; LaCluyze, A. P.; Berger, E.; Chandra, P.; Fox, D. B.; Prochaska, J. X.; Kasliwal, M. M.; Kulkarni, S. R.

    2011-05-01

    We present broadband (radio, optical, and X-ray) light curves and spectra of the afterglows of four long-duration gamma-ray bursts (GRBs; GRBs 090323, 090328, 090902B, and 090926A) detected by the Gamma-Ray Burst Monitor and Large Area Telescope (LAT) instruments on the Fermi satellite. With its wide spectral bandpass, extending to GeV energies, Fermi is sensitive to GRBs with very large isotropic energy releases (10{sup 54} erg). Although rare, these events are particularly important for testing GRB central-engine models. When combined with spectroscopic redshifts, our afterglow data for these four events are able to constrain jet collimation angles, the density structure of the circumburst medium, and both the true radiated energy release and the kinetic energy of the outflows. In agreement with our earlier work, we find that the relativistic energy budget of at least one of these events (GRB 090926A) exceeds the canonical value of 10{sup 51} erg by an order of magnitude. Such energies pose a severe challenge for models in which the GRB is powered by a magnetar or a neutrino-driven collapsar, but remain compatible with theoretical expectations for magnetohydrodynamical collapsar models (e.g., the Blandford-Znajek mechanism). Our jet opening angles ({theta}) are similar to those found for pre-Fermi GRBs, but the large initial Lorentz factors ({Gamma}{sub 0}) inferred from the detection of GeV photons imply {theta}{Gamma}{sub 0} {approx} 70-90, values which are above those predicted in magnetohydrodynamic models of jet acceleration. Finally, we find that these Fermi-LAT events preferentially occur in a low-density circumburst environment, and we speculate that this might result from the lower mass-loss rates of their lower-metallicity progenitor stars. Future studies of Fermi-LAT afterglows at radio wavelengths with the order-of-magnitude improvement in sensitivity offered by the Extended Very Large Array should definitively establish the relativistic energy

  17. Non-equilibrium vibrational and electron energy distribution functions in mtorr, high-electron-density nitrogen discharges and afterglows

    NASA Astrophysics Data System (ADS)

    Capitelli, M.; Colonna, G.; D’Ammando, G.; Laricchiuta, A.; Pietanza, L. D.

    2017-03-01

    Non-equilibrium vibrational distributions (vdf) and non-equilibrium electron energy distribution functions (eedf) in a nitrogen plasma at low pressure (mtorr) have been calculated by using a time-dependent plasma physics model coupled to the Boltzmann equation and heavy particle kinetics. Different case studies have been selected showing the non-equilibrium character of both vdf and eedf under discharge and post-discharge conditions in the presence of large concentrations of electrons. Particular attention is devoted to the electron-molecule resonant vibrational excitation cross sections acting in the whole vibrational ladder. The results in the post-discharge conditions show the interplay of superelastic vibrational and electronic collisions in forming structures in the eedf. The link between the present results in the mtorr afterglow regime with the existing eedf in the torr and atmospheric regimes is discussed.

  18. GRB 021211 as a Faint Analogue of GRB 990123: Exploring the Similarities and Differences in the Optical Afterglows

    NASA Technical Reports Server (NTRS)

    Holland, Stephen T.; Bersier, David; Bloom, J. S.; Garnavich, Peter M.; Caldwell, Nelson; Challis, Peter; Kirshner, Robert; Luhman, Kevin; McLeod, Brian; Stanek, K. Z.

    2004-01-01

    We present BVR(sub c)JHK(sub s) photometry of the optical afterglow of the gamma-ray burst GRB 021211 taken at the Magellan, MMT, and WIYN observatories between 0.7 and 50 days after the burst. We find an intrinsic spectral slope at optical and near-infrared wavelengths of 0.69 +/- 0.14 at 0.87 days. The optical decay during the first day is almost identical to that of GRB 990123 except that GRB 021211's optical afterglow was intrinsically approximately 38 times fainter and the transition from the reverse shock to the forward shock may have occurred earlier than it did for GRB 990123. We find no evidence for a jet break or the cooling break passing through optical frequencies during the first day after the burst. There is weak evidence for a break in the J-band decay between 0.89 and 1.87 days which may be due to a jet. The optical and infrared data are consistent with a relativistic fireball where the shocked electrons are in the slow cooling regime and the electron index is 2.3 +/- 0.1. The burst appears to have occurred in a homogeneous ambient medium. Our analysis suggests that the jet of GRB 021211 may have a small opening angle (1.4 deg-4.4 deg) and that the total gamma-ray energy is much less than the canonical value of 1.33 x 10(exp 51) erg. If, this is the case then most of the energy of the burst may be in another form such as a frozen magnetic field, in supernova ejecta, or in a second jet component. The host galaxy of GRB 021211 is subluminous and has a star formation rate of at least 1 solar mass/yr.

  19. The Afterglow, Energetics, and Host Galaxy of the Short-Hard Gamma-Ray Burst 051221a

    NASA Astrophysics Data System (ADS)

    Soderberg, A. M.; Berger, E.; Kasliwal, M.; Frail, D. A.; Price, P. A.; Schmidt, B. P.; Kulkarni, S. R.; Fox, D. B.; Cenko, S. B.; Gal-Yam, A.; Nakar, E.; Roth, K. C.

    2006-10-01

    We present detailed optical, X-ray, and radio observations of the bright afterglow of the short gamma-ray burst 051221a obtained with Gemini, Swift XRT, and the Very Large Array, as well as optical spectra from which we measure the redshift of the burst, z=0.5464. At this redshift the isotropic-equivalent prompt energy release was about 1.5×1051 ergs, and using a standard afterglow synchrotron model, we find that the blast wave kinetic energy is similar, EK,iso~8.4×1051 ergs. An observed jet break at t~5 days indicates that the opening angle is θj~7deg and the total beaming-corrected energy is therefore ~2.5×1049 ergs, comparable to the values inferred for previous short GRBs. We further show that the burst experienced an episode of energy injection by a factor of 3.4 between t=1.4 and 3.4 hr, which was accompanied by reverse shock emission in the radio band. This result provides continued evidence that the central engines of short GRBs may be active significantly longer than the duration of the burst and/or produce a wide range of Lorentz factors. Finally, we show that the host galaxy is actively forming stars at a rate of about 1.6 Msolar yr-1, yet exhibits evidence for an appreciable population of old stars (~1 Gyr) and near-solar metallicity. These properties are intermediate between those of long GRB hosts and previous short burst hosts. The lack of bright supernova emission and the low circumburst density (n~10-3 cm-3), however, continue to support the idea that short bursts are not related to massive stellar death. Given that the total energy release is larger than the predicted yield for a neutrino annihilation mechanism, this suggests that magnetohydrodynamic processes may be required to power the burst.

  20. Computational study of the afterglow in single and sequential pulsing of an atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Hasan, M. I.; Bradley, J. W.

    2015-10-01

    The spatial distribution of charged species in the afterglow of a helium plasma jet impinging atmospheric air has been computed using a 2D axisymmetric fluid model. The model is solved for two consecutive pulse periods of a rectangular voltage waveform (duration of 60 ns) and for two different frequencies (25 and 50 kHz). The most abundant ionic species in the afterglow are found to be \\text{O}2+ and \\text{O}2- with their concentrations increasing by about an order of magnitude (up to about 1018 m-3 and 1017 m-3 respectively) in the initial 1 μs. In the first pulse, these species form a halo around the diffusing He+ and electron rich central channel, the shape of the former being strongly correlated with the shape of He-air mixing layer computed using a hydrodynamic model. In the next pulse, this general configuration is also observed; however \\text{O}2+ is more concentrated on the axis of the jet, this being due to influence of residual electrons in the central channel. For \\text{O}2- there is little difference in their spatial distribution compared to the initial pulse. For higher frequency pulsing, the higher concentration of residual electrons lowers the necessary ignition electric field reducing the concentrations (by 25%) of charged species in a period of the applied waveform. This work provides new information on the concentration and distribution of ionic species generated by atmospheric-pressure capillary discharges of interest to those developing such sources for range of applications, particularly in the field of plasma medicine.

  1. Non-Maxwellian electron energy distribution function in He, He/Ar, He/Xe/H2 and He/Xe/D2 low temperature afterglow plasma

    NASA Astrophysics Data System (ADS)

    Plasil, R.; Korolov, I.; Kotrik, T.; Dohnal, P.; Bano, G.; Donko, Z.; Glosik, J.

    2009-08-01

    Experimental studies of the electron energy distribution function “EEDF” under well defined conditions in flowing afterglow plasma, using a Langmuir probe are reported. The EEDF is measured in He2 + and Ar+ dominated plasmas and in XeH+ and XeD+ dominated recombining plasmas. He is used as a buffer gas at medium pressures in all experiments (1600 Pa, 250 K). The deviation of the measured EEDF from Maxwellian distribution is shown to depend on plasma composition and on the processes governing the plasma decay. The influence of energetic electrons produced during the plasma decay on the body and tail of the EEDF is observed. The mechanism of energy balance in afterglow plasma is discussed.

  2. Flowing-afterglow study of electron-ion recombination of para-H3(+) and ortho-H3(+) ions at temperatures from 60 K to 300 K.

    PubMed

    Hejduk, Michal; Dohnal, Petr; Rubovič, Peter; Kálosi, Ábel; Plašil, Radek; Johnsen, Rainer; Glosík, Juraj

    2015-07-28

    Detailed measurements employing a combination of a cryogenic flowing afterglow with Langmuir probe (Cryo-FALP II) and a stationary afterglow with near-infrared absorption spectroscopy (SA-CRDS) show that binary electron recombination of para-H3(+) and ortho-H3(+) ions occurs with significantly different rate coefficients, (p)αbin and (o)αbin, especially at very low temperatures. The measurements cover temperatures from 60 K to 300 K. At the lowest temperature of 60 K, recombination of para-H3(+) is at least three times faster than that of ortho-H3(+) ((p)αbin=(1.8±0.4)×10(-7) cm(3) s(-1) vs. (o)αbin=(0-0 (+5))×10(-8) cm(3) s(-1)).

  3. Flowing-afterglow study of electron-ion recombination of para- H3 + and ortho- H3 + ions at temperatures from 60 K to 300 K

    NASA Astrophysics Data System (ADS)

    Hejduk, Michal; Dohnal, Petr; Rubovič, Peter; Kálosi, Ábel; Plašil, Radek; Johnsen, Rainer; Glosík, Juraj

    2015-07-01

    Detailed measurements employing a combination of a cryogenic flowing afterglow with Langmuir probe (Cryo-FALP II) and a stationary afterglow with near-infrared absorption spectroscopy (SA-CRDS) show that binary electron recombination of para-H3 + and ortho-H3 + ions occurs with significantly different rate coefficients, pαbin and oαbin, especially at very low temperatures. The measurements cover temperatures from 60 K to 300 K. At the lowest temperature of 60 K, recombination of para-H3 + is at least three times faster than that of ortho-H3 + ( p α bin = ( 1 . 8 ± 0 . 4 ) × 1 0 - 7 cm 3 s - 1 vs . o α bin = ( 0- 0 + 5 ) × 1 0 - 8 cm 3 s - 1 ) .

  4. On the Early-Time X-Ray Spectra of Swift Afterglows. I. Evidence for Anomalous Soft X-Ray Emission

    NASA Astrophysics Data System (ADS)

    Butler, N. R.

    2007-02-01

    We have conducted a thorough and blind search for emission lines in >70 Swift X-ray afterglows of total exposure ~107 s. We find that most afterglows are consistent with pure power laws plus extinction. Significant outliers to the population exist at the 5%-10% level and have anomalously soft, possibly thermal spectra. Four bursts are singled out via possible detections of two to five lines: GRB 060218, GRB 060202, GRB 050822, and GRB 050714B. Alternatively, a blackbody model with kT~0.1-0.5 keV can describe the soft emission in each afterglow. The most significant soft-component detections in the full data set of ~2000 spectra correspond to GRB 060218/SN 2006aj, with line significances ranging up to ~20 σ. A thermal plasma model fit to the data indicates that the flux is primarily due to L-shell transitions of Fe at roughly solar abundance. We associate (>4 σ significant) line triggers in the three other events with K-shell transitions in light metals. We favor a model where the possible line emission in these afterglows arises from the mildly relativistic cocoon of matter surrounding the GRB jet as it penetrates and exits the surface of the progenitor star. The emitting material in each burst is at a similar distance ~1012-1013 cm, a similar density ~1017 cm-3, and subject to a similar flux of ionizing radiation. The lines may correlate with the X-ray flaring. For the blackbody interpretation, the soft flux may arise from breakout of the GRB shock or plasma cocoon from the progenitor stellar wind, as recently suggested for GRB 060218 (Campana et al. 2006). Due to the low z of GRB 060218, bursts faint in gamma rays with fluxes dominated by this soft X-ray component could outnumber classical GRBs 100 to 1.

  5. Application of Langmuir Probe for Study of Recombination of D3+ Ions with Electrons in He-Ar-D2 Stationary and Flowing Afterglow Plasma

    NASA Astrophysics Data System (ADS)

    Tichy, M.; Poterya, V.; Plasil, R.; Pysanenko, A.; Kudrna, P.; Novotny, O.; Zakouril, P.; Glosik, J.

    2003-06-01

    We report measurements of the rate coefficient for recombination of D3+ and D5+ with electrons in He-Ar-D2 plasma. Two afterglow experiments, flowing afterglow and stationary afterglow were used to cover large extent of pressures of He buffer gas (2-10 Torr) and large extent of partial number densities of D2 (5×1010-3×1015cm-3). Langmuir probes and mass spectrometers were used to monitor decay of the plasma during the afterglow. The observed rate coefficient is dependent on the deuterium number density indicating that third-body-assisted recombination is efficient and significantly contributes to recombination when sufficient number density of deuterium is present. At low D2 number densities the ions D3+ dominate the ion composition and electron density decay is controlled by recombination of D3+ with recombination rate coefficient α(D3+). At higher D2 number densities and lower temperatures D5+ are formed and electron density decay is controlled by recombination of D5+ ions with recombination rate coefficient α(D5+). The overall effective recombination rate coefficient αeff as a function of D2 number density was measured and from this dependence the rates α(D3+) and α(D5+) at several temperatures were determined. Obtained pressure dependencies are in good agreement with thermodynamic data. When the deuterium number density is decreased down to 5×1010cm-3, the rate coefficient also decreases to αeff ˜4×10-9 cm3s-1. These data indicate that the binary dissociative recombination of D3+ is very slow with αDR <4×10-9 cm3s-1. The observation of an additional de-ionization process proceeding via formation of D5+ and its recombination is also reported.

  6. Characterization of afterglow-related spectroscopic effects in vacuum sintered Tb3+, Sr2+ co-doped Lu2O3 ceramics

    NASA Astrophysics Data System (ADS)

    Chen, Shi; Yang, Yan; Zhou, Guohong; Wu, Yiquan; Liu, Peng; Zhang, Fang; Wang, Shiwei; Trojan-Piegza, Joanna; Zych, Eugeniusz

    2012-12-01

    Persistent luminescence phosphors, Tb3+, Sr2+ co-doped Lu2O3 ceramics were fabricated under vacuum at 1870 °C. A strong green color afterglow could be observed after excitation with 254 nm UV radiation. The afterglow was found to be roughly doubled in intensity upon stimulation with violet or blue-green photons (˜400-600 nm) as well as upon IR radiation (˜800-980 nm). Hence, the enhancement of the green afterglow could also be attained by means of natural sunlight. Short wavelength UV radiation was found to induce an extrinsic absorption band below about 600 nm and extending into the deep UV. This was mirrored by a simultaneous decrease of the absorption by Tb3+ around 230-320 nm. The extrinsic absorption seemed to contain at least two overlapping components which supposedly resulted from a band related to Tb4+/Tb3+-h and a feature resulting from F/F+ centers created upon irradiation with short UV. This absorption was shown to be reversible, as it disappeared after a short heat treatment at about 300 °C as well as with continuous irradiation of ˜400 nm radiation.

  7. Long-lived plasma and fast quenching of N2(C3Π u ) by electrons in the afterglow of a nanosecond capillary discharge in nitrogen

    NASA Astrophysics Data System (ADS)

    Lepikhin, N. D.; Klochko, A. V.; Popov, N. A.; Starikovskaia, S. M.

    2016-08-01

    Quenching of electronically excited nitrogen state, {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u},{{v}\\prime}=0\\right) , in the afterglow of nanosecond capillary discharge in pure nitrogen is studied. It is found experimentally that an additional collisional mechanism appears and dominates at high specific deposited energies leading to the anomalously fast quenching of the {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u}\\right) in the afterglow. On the basis of obtained experimental data and of the analysis of possible quenching agents, it is concluded that the anomalously fast deactivation of the {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u}\\right) can be explained by quenching by electrons. Long-lived plasma at time scale of hundreds nanoseconds after the end of the pulse is observed. High electron densities, about 1014 cm-3 at 27 mbar, are sustained by reactions of associative ionization. Kinetic 1D numerical modeling and comparison of calculated results with experimentally measured electric fields in the second high-voltage pulse 250 ns after the initial pulse, and electron density measurements in the afterglow confirm the validity of the suggested mechanism.

  8. iPTF14yb: The First Discovery of a Gamma-Ray Burst Afterglow Independent of a High-Energy Trigger

    SciTech Connect

    Cenko, S. Bradley; Urban, Alex L.; Perley, Daniel A.; Horesh, Assaf; Corsi, Alessandra; Fox, Derek B.; Cao, Yi; Kasliwal, Mansi M.; Lien, Amy; Arcavi, Iair; Bloom, Joshua S.; Butler, Nat R.; Cucchiara, Antonino; Diego, José A. de; Filippenko, Alexei V.; Gal-Yam, Avishay; Gehrels, Neil; Georgiev, Leonid; Gonzalez, J. Jesus; Graham, John F.; Greiner, Jochen; Kann, D. Alexander; Klein, Christopher R.; Knust, Fabian; Kulkarni, S. R.; Kutyrev, Alexander; Laher, Russ; Lee, William H.; Nugent, Peter E.; Xavier Prochaska, J.; Rubin, Adam; Urata, Yuji; Varela, Karla; Watson, Alan M.; Wozniak, Przemek R.

    2015-04-20

    We report here the discovery by the Intermediate Palomar Transient Factory (iPTF) of iPTF14yb, a luminous (Msub>r ≈ ₋27.8 mag), cosmological (redshift 1.9733), rapidly fading optical transient. We demonstrate, based on probabilistic arguments and a comparison with the broader population, that iPTF14yb is the optical afterglow of the long-duration gamma-ray burst GRB140226A. This marks the rst unambiguous discovery of a GRB afterglow prior to (and thus entirely independent of) an associated high-energy trigger. We estimate the rate of iPTF14yb-like sources (i.e., cosmologically dis- tant relativistic explosions) based on iPTF observations, inferring an all-sky value of $R_{rel}$ = 610yr-1 (68% con dence interval of 110{2000 yr-1). Our derived rate is consistent (within the large uncer- tainty) with the all-sky rate of on-axis GRBs derived by the Swift satellite. Finally, we brie y discuss the implications of the nondetection to date of bona de \\orphan" afterglows (i.e., those lacking de- tectable high-energy emission) on GRB beaming and the degree of baryon loading in these relativistic jets.

  9. iPTF14yb: The First Discovery of a Gamma-Ray Burst Afterglow Independent of a High-Energy Trigger

    DOE PAGES

    Cenko, S. Bradley; Urban, Alex L.; Perley, Daniel A.; ...

    2015-04-20

    We report here the discovery by the Intermediate Palomar Transient Factory (iPTF) of iPTF14yb, a luminous (Msub>r ≈ ₋27.8 mag), cosmological (redshift 1.9733), rapidly fading optical transient. We demonstrate, based on probabilistic arguments and a comparison with the broader population, that iPTF14yb is the optical afterglow of the long-duration gamma-ray burst GRB140226A. This marks the rst unambiguous discovery of a GRB afterglow prior to (and thus entirely independent of) an associated high-energy trigger. We estimate the rate of iPTF14yb-like sources (i.e., cosmologically dis- tant relativistic explosions) based on iPTF observations, inferring an all-sky value ofmore » $$R_{rel}$$ = 610yr-1 (68% con dence interval of 110{2000 yr-1). Our derived rate is consistent (within the large uncer- tainty) with the all-sky rate of on-axis GRBs derived by the Swift satellite. Finally, we brie y discuss the implications of the nondetection to date of bona de \\orphan" afterglows (i.e., those lacking de- tectable high-energy emission) on GRB beaming and the degree of baryon loading in these relativistic jets.« less

  10. First limits on the very-high energy gamma-ray afterglow emission of a fast radio burst. H.E.S.S. observations of FRB 150418

    NASA Astrophysics Data System (ADS)

    H. E. S. S. Collaboration; Abdalla, H.; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Andersson, T.; Angüner, E. O.; Arakawa, M.; Arrieta, M.; Aubert, P.; Backes, M.; Balzer, A.; Barnard, M.; Becherini, Y.; Becker Tjus, J.; Berge, D.; Bernhard, S.; Bernlöhr, K.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Büchele, M.; Bulik, T.; Capasso, M.; Carr, J.; Casanova, S.; Cerruti, M.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chen, A.; Chevalier, J.; Chrétien, M.; Coffaro, M.; Colafrancesco, S.; Cologna, G.; Condon, B.; Conrad, J.; Cui, Y.; Davids, I. D.; Decock, J.; Degrange, B.; Deil, C.; Devin, J.; Dewilt, P.; Dirson, L.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O.'c.; Dutson, K.; Dyks, J.; Edwards, T.; Egberts, K.; Eger, P.; Ernenwein, J.-P.; Eschbach, S.; Farnier, C.; Fegan, S.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Funk, S.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Goyal, A.; Grondin, M.-H.; Hahn, J.; Haupt, M.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hinton, J. A.; Hofmann, W.; Hoischen, C.; Holler, M.; Horns, D.; Ivascenko, A.; Iwasaki, H.; Jacholkowska, A.; Jamrozy, M.; Janiak, M.; Jankowsky, D.; Jankowsky, F.; Jingo, M.; Jogler, T.; Jouvin, L.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katsuragawa, M.; Katz, U.; Kerszberg, D.; Khangulyan, D.; Khélifi, B.; Kieffer, M.; King, J.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Kraus, M.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lees, J.-P.; Lefaucheur, J.; Lefranc, V.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Leser, E.; Lohse, T.; Lorentz, M.; Liu, R.; López-Coto, R.; Lypova, I.; Marandon, V.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Morå, K.; Moulin, E.; Murach, T.; Nakashima, S.; de Naurois, M.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Öttl, S.; Ohm, S.; Ostrowski, M.; Oya, I.; Padovani, M.; Panter, M.; Parsons, R. D.; Pekeur, N. W.; Pelletier, G.; Perennes, C.; Petrucci, P.-O.; Peyaud, B.; Piel, Q.; Pita, S.; Poon, H.; Prokhorov, D.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reimer, A.; Reimer, O.; Renaud, M.; de Los Reyes, R.; Richter, S.; Rieger, F.; Romoli, C.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Saito, S.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Seglar-Arroyo, M.; Settimo, M.; Seyffert, A. S.; Shafi, N.; Shilon, I.; Simoni, R.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stycz, K.; Sushch, I.; Takahashi, T.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tibaldo, L.; Tiziani, D.; Tluczykont, M.; Trichard, C.; Tsuji, N.; Tuffs, R.; Uchiyama, Y.; van der Walt, D. J.; van Eldik, C.; van Rensburg, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zanin, R.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Ziegler, A.; Żywucka, N.; Superb Collaboration; Jankowski, F.; Keane, E. F.; Petroff, E.

    2017-01-01

    Aims: Following the detection of the fast radio burst FRB150418 by the SUPERB project at the Parkes radio telescope, we aim to search for very-high energy gamma-ray afterglow emission. Methods: Follow-up observations in the very-high energy gamma-ray domain were obtained with the H.E.S.S. imaging atmospheric Cherenkov telescope system within 14.5 h of the radio burst. Results: The obtained 1.4 h of gamma-ray observations are presented and discussed. At the 99% C.L. we obtained an integral upper limit on the gamma-ray flux of Φγ(E > 350 GeV) < 1.33 × 10-8 m-2 s-1. Differential flux upper limits as function of the photon energy were derived and used to constrain the intrinsic high-energy afterglow emission of FRB 150418. Conclusions: No hints for high-energy afterglow emission of FRB 150418 were found. Taking absorption on the extragalactic background light into account and assuming a distance of z = 0.492 based on radio and optical counterpart studies and consistent with the FRB dispersion, we constrain the gamma-ray luminosity at 1 TeV to L < 5.1 × 1047 erg/s at 99% C.L.

  11. iPTF14yb: The First Discovery of a Gamma-Ray Burst Afterglow Independent of a High-Energy Trigger

    NASA Technical Reports Server (NTRS)

    Cenko, S. Bradley; Urban, Alex L.; Perley, Daniel A.; Horesh, Assaf; Corsi, Alessandra; Fox, Derek B.; Cao, Yi; Kasliwal, Mansi M.; Lien, Amy; Arcavi, Iair; Bloom, Joshua S.; Butler, Nat R.; Cucchiara, Antonino; De Diego, Jose A.; Filippenko, Alexei V.; Gal-Yam, Avishay; Gehrels, Neil; Georgiev, Leonid; Gonzalez, J. Jesus; Graham, John F.; Greiner, Jochen; Kann, D. Alexander; Klein, Christopher R.; Knust, Fabian; Kutyrev, Alexander

    2015-01-01

    We report here the discovery by the Intermediate Palomar Transient Factory (iPTF) of iPTF14yb, a luminous (Mr >> -27.8 mag), cosmological (redshift 1.9733), rapidly fading optical transient. We demonstrate, based on probabilistic arguments and a comparison with the broader population, that iPTF14yb is the optical afterglow of the long-duration gamma-ray burst GRB 140226A. This marks the first unambiguous discovery of a GRB afterglow prior to (and thus entirely independent of) an associated high-energy trigger. We estimate the rate of iPTF14yb-like sources (i.e., cosmologically distant relativistic explosions) based on iPTF observations, inferring an all-sky value of Rrel = 610/yr (68% confidence interval of 110-2000/yr). Our derived rate is consistent (within the large uncertainty) with the all-sky rate of on-axis GRBs derived by the Swift satellite. Finally, we briefly discuss the implications of the nondetection to date of bona fide "orphan" afterglows (i.e., those lacking detectable high-energy emission) on GRB beaming and the degree of baryon loading in these relativistic jets.

  12. THERMAL EMISSION IN THE EARLY X-RAY AFTERGLOWS OF GAMMA-RAY BURSTS: FOLLOWING THE PROMPT PHASE TO LATE TIMES

    SciTech Connect

    Friis, Mette; Watson, Darach E-mail: darach@dark-cosmology.dk

    2013-07-01

    Thermal radiation, peaking in soft X-rays, has now been detected in a handful of gamma-ray burst (GRB) afterglows and has to date been interpreted as shock break-out of the GRB's progenitor star. We present a search for thermal emission in the early X-ray afterglows of a sample of Swift bursts selected by their brightness in X-rays at early times. We identify a clear thermal component in eight GRBs and track the evolution. We show that at least some of the emission must come from highly relativistic material since two show an apparent super-luminal expansion of the thermal component. Furthermore, we determine very large luminosities and high temperatures for many of the components-too high to originate in a supernova shock break-out. Instead, we suggest that the component may be modeled as late photospheric emission from the jet, linking it to the apparently thermal component observed in the prompt emission of some GRBs at gamma-ray and hard X-ray energies. By comparing the parameters from the prompt emission and the early afterglow emission, we find that the results are compatible with the interpretation that we are observing the prompt quasi-thermal emission component in soft X-rays at a later point in its evolution.

  13. The low-extinction afterglow in the solar-metallicity host galaxy of γ-ray burst 110918A

    NASA Astrophysics Data System (ADS)

    Elliott, J.; Krühler, T.; Greiner, J.; Savaglio, S.; Olivares, F.; Rau, E. A.; de Ugarte Postigo, A.; Sánchez-Ramírez, R.; Wiersema, K.; Schady, P.; Kann, D. A.; Filgas, R.; Nardini, M.; Berger, E.; Fox, D.; Gorosabel, J.; Klose, S.; Levan, A.; Nicuesa Guelbenzu, A.; Rossi, A.; Schmidl, S.; Sudilovsky, V.; Tanvir, N. R.; Thöne, C. C.

    2013-08-01

    Galaxies selected through long γ-ray bursts (GRBs) could be of fundamental importance when mapping the star formation history out to the highest redshifts. Before using them as efficient tools in the early Universe, however, the environmental factors that govern the formation of GRBs need to be understood. Metallicity is theoretically thought to be a fundamental driver in GRB explosions and energetics, but it is still, even after more than a decade of extensive studies, not fully understood. This is largely related to two phenomena: a dust-extinction bias, which prevented high-mass and thus likely high-metallicity GRB hosts from being detected in the first place, and a lack of efficient instrumentation, which limited spectroscopic studies, including metallicity measurements, to the low-redshift end of the GRB host population. The subject of this work is the very energetic GRB 110918A (Eγ,iso = 1.9 × 1054 erg), for which we measure a redshift of z = 0.984. GRB 110918A gave rise to a luminous afterglow with an intrinsic spectral slope of β = 0.70, which probed a sight-line with little extinction (AGRBV = 0.16 mag) and soft X-ray absorption (NH,X = (1.6 ± 0.5) × 1021 cm-2) typical of the established distributions of afterglow properties. However, photometric and spectroscopic follow-up observations of the galaxy hosting GRB 110918A, including optical/near-infrared photometry with the Gamma-Ray burst Optical Near-infrared Detector and spectroscopy with the Very Large Telescope/X-shooter, reveal an all but average GRB host in comparison to the z ~ 1 galaxies selected through similar afterglows to date. It has a large spatial extent with a half-light radius of R1/2 ~ 10 kpc, the highest stellar mass for z < 1.9 (log (M∗/M⊙) = 10.68 ± 0.16), and an Hα-based star formation rate of SFRHα = 41+28-16M⊙ yr-1. We measure a gas-phase extinction of AgasV ~ 1.8 mag through the Balmer decrement and one of the largest host-integrated metallicities ever of around solar

  14. The Afterglow and Early-type Host Galaxy of the Short GRB 150101B at z = 0.1343

    NASA Astrophysics Data System (ADS)

    Fong, W.; Margutti, R.; Chornock, R.; Berger, E.; Shappee, B. J.; Levan, A. J.; Tanvir, N. R.; Smith, N.; Milne, P. A.; Laskar, T.; Fox, D. B.; Lunnan, R.; Blanchard, P. K.; Hjorth, J.; Wiersema, K.; van der Horst, A. J.; Zaritsky, D.

    2016-12-01

    We present the discovery of the X-ray and optical afterglows of the short-duration GRB 150101B, pinpointing the event to an early-type host galaxy at z = 0.1343 ± 0.0030. This makes GRB 150101B the most nearby short gamma-ray burst (GRB) with an early-type host galaxy discovered to date. Fitting the spectral energy distribution of the host galaxy results in an inferred stellar mass of ≈ 7× {10}10 {M}⊙ , stellar population age of ≈2-2.5 Gyr, and star formation rate of ≲0.4 M ⊙ yr-1. The host of GRB 150101B is one of the largest and most luminous short GRB host galaxies, with a B-band luminosity of ≈ 4.3{L}* and half-light radius of ≈8 kpc. GRB 150101B is located at a projected distance of 7.35 ± 0.07 kpc from its host center and lies on a faint region of its host rest-frame optical light. Its location, combined with the lack of associated supernova, is consistent with an NS-NS/NS-BH merger progenitor. From modeling the evolution of the broadband afterglow, we calculate isotropic-equivalent gamma-ray and kinetic energies of ≈ 1.3× {10}49 erg and ≈ (6{--}14)× {10}51 erg, respectively, a circumburst density of ≈ (0.8{--}4)× {10}-5 cm-3, and a jet opening angle of ≳9°. Using observations extending to ≈30 days, we place upper limits of ≲ (2{--}4)× {10}41 erg s-1 on associated kilonova emission. We compare searches following previous short GRBs to existing kilonova models and demonstrate the difficulty of performing effective kilonova searches from cosmological short GRBs using current ground-based facilities. We show that at the Advanced LIGO/VIRGO horizon distance of 200 Mpc, searches reaching depths of ≈23-24 AB mag are necessary to probe a meaningful range of kilonova models.

  15. Sterilization/disinfection of medical devices using plasma: the flowing afterglow of the reduced-pressure N2-O2 discharge as the inactivating medium

    NASA Astrophysics Data System (ADS)

    Moisan, Michel; Boudam, Karim; Carignan, Denis; Kéroack, Danielle; Levif, Pierre; Barbeau, Jean; Séguin, Jacynthe; Kutasi, Kinga; Elmoualij, Benaïssa; Thellin, Olivier; Zorzi, Willy

    2013-07-01

    Potential sterilization/disinfection of medical devices (MDs) is investigated using a specific plasma process developed at the Université de Montréal over the last decade. The inactivating medium of the microorganisms is the flowing afterglow of a reduced-pressure N2-O2 discharge, which provides, as the main biocidal agent, photons over a broad ultraviolet (UV) wavelength range. The flowing afterglow is considered less damaging to MDs than the discharge itself. Working at gas pressures in the 400—700 Pa range (a few torr) ensures, through species diffusion, the uniform filling of large volume chambers with the species outflowing from the discharge, possibly allowing batch processing within them. As a rule, bacterial endospores are used as bio-indicators (BI) to validate sterilization processes. Under the present operating conditions, Bacillus atrophaeus is found to be the most resistant one and is therefore utilized as BI. The current paper reviews the main experimental results concerning the operation and characterization of this sterilizer/disinfector, updating and completing some of our previously published papers. It uses modeling results as guidelines, which are particularly useful when the corresponding experimental data are not (yet) available, hopefully leading to more insight into this plasma afterglow system. The species flowing out of the N2-O2 discharge can be divided into two groups, depending on the time elapsed after they left the discharge zone as they move toward the chamber, namely the early afterglow and the late afterglow. The early flowing afterglow from a pure N2 discharge (also called pink afterglow) is known to be comprised of N2+ and N4+ ions. In the present N2-O2 mixture discharge, NO+ ions are additionally generated, with a lifetime that extends over a longer period than that of the nitrogen molecular ions. We shall suppose that the disappearance of the NO+ ions marks the end of the early afterglow regime, thereby stressing our intent

  16. Flowing atmospheric pressure afterglow combined with laser ablation for direct analysis of compounds separated by thin-layer chromatography.

    PubMed

    Cegłowski, Michał; Smoluch, Marek; Reszke, Edward; Silberring, Jerzy; Schroeder, Grzegorz

    2016-01-01

    A thin-layer chromatography-mass spectrometry (TLC-MS) setup for characterization of low molecular weight compounds separated on standard TLC plates has been constructed. This new approach successfully combines TLC separation, laser ablation, and ionization using flowing atmospheric pressure afterglow (FAPA) source. For the laser ablation, a low-priced 445-nm continuous-wave diode laser pointer, with a power of 1 W, was used. The combination of the simple, low-budget laser pointer and the FAPA ion source has made this experimental arrangement broadly available, also for small laboratories. The approach was successfully applied for the characterization of low molecular weight compounds separated on TLC plates, such as a mixture of pyrazole derivatives, alkaloids (nicotine and sparteine), and an extract from a drug tablet consisting of paracetamol, propyphenazone, and caffeine. The laser pointer used was capable of ablating organic compounds without the need of application of any additional substances (matrices, staining, etc.) on the TLC spots. The detection limit of the proposed method was estimated to be 35 ng/cm(2) of a pyrazole derivative.

  17. A flowing atmospheric pressure afterglow as an ion source coupled to a differential mobility analyzer for volatile organic compound detection.

    PubMed

    Bouza, Marcos; Orejas, Jaime; López-Vidal, Silvia; Pisonero, Jorge; Bordel, Nerea; Pereiro, Rosario; Sanz-Medel, Alfredo

    2016-05-23

    Atmospheric pressure glow discharges have been widely used in the last decade as ion sources in ambient mass spectrometry analyses. Here, an in-house flowing atmospheric pressure afterglow (FAPA) has been developed as an alternative ion source for differential mobility analysis (DMA). The discharge source parameters (inter-electrode distance, current and helium flow rate) determining the atmospheric plasma characteristics have been optimized in terms of DMA spectral simplicity with the highest achievable sensitivity while keeping an adequate plasma stability and so the FAPA working conditions finally selected were: 35 mA, 1 L min(-1) of He and an inter-electrode distance of 8 mm. Room temperature in the DMA proved to be adequate for the coupling and chemical analysis with the FAPA source. Positive and negative ions for different volatile organic compounds were tested and analysed by FAPA-DMA using a Faraday cup as a detector and proper operation in both modes was possible (without changes in FAPA operational parameters). The FAPA ionization source showed simpler ion mobility spectra with narrower peaks and a better, or similar, sensitivity than conventional UV-photoionization for DMA analysis in positive mode. Particularly, the negative mode proved to be a promising field of further research for the FAPA ion source coupled to ion mobility, clearly competitive with other more conventional plasmas such as corona discharge.

  18. An optical spectrum of the afterglow of a gamma-ray burst at a redshift of z = 6.295.

    PubMed

    Kawai, N; Kosugi, G; Aoki, K; Yamada, T; Totani, T; Ohta, K; Iye, M; Hattori, T; Aoki, W; Furusawa, H; Hurley, K; Kawabata, K S; Kobayashi, N; Komiyama, Y; Mizumoto, Y; Nomoto, K; Noumaru, J; Ogasawara, R; Sato, R; Sekiguchi, K; Shirasaki, Y; Suzuki, M; Takata, T; Tamagawa, T; Terada, H; Watanabe, J; Yatsu, Y; Yoshida, A

    2006-03-09

    The prompt gamma-ray emission from gamma-ray bursts (GRBs) should be detectable out to distances of z > 10 (ref. 1), and should therefore provide an excellent probe of the evolution of cosmic star formation, reionization of the intergalactic medium, and the metal enrichment history of the Universe. Hitherto, the highest measured redshift for a GRB has been z = 4.50 (ref. 5). Here we report the optical spectrum of the afterglow of GRB 050904 obtained 3.4 days after the burst; the spectrum shows a clear continuum at the long-wavelength end of the spectrum with a sharp cut-off at around 9,000 A due to Lyman alpha absorption at z approximately 6.3 (with a damping wing). A system of absorption lines of heavy elements at z = 6.295 +/- 0.002 was also detected, yielding the precise measurement of the redshift. The Si ii fine-structure lines suggest a dense, metal-enriched environment around the progenitor of the GRB.

  19. Kinetics of excited states and radicals in a nanosecond pulse discharge and afterglow in nitrogen and air

    NASA Astrophysics Data System (ADS)

    Shkurenkov, Ivan; Burnette, David; Lempert, Walter R.; Adamovich, Igor V.

    2014-12-01

    The present kinetic modelling calculation results provide key new insights into the kinetics of vibrational excitation of nitrogen and plasma chemical reactions in nanosecond pulse, ‘diffuse filament’ discharges in nitrogen and dry air at a moderate energy loading per molecule, ˜0.1 eV per molecule. It is shown that it is very important to take into account Coulomb collisions between electrons because they change the electron energy distribution function and, as a result, strongly affect populations of excited states and radical concentrations in the discharge. The results demonstrate that the apparent transient rise of N2 ‘first level’ vibrational temperature after the discharge pulse, as detected in the experiments, is due to the net downward V-V energy transfer in N2-N2 collisions, which increases the N2(X 1Σ, v = 1) population. Finally, a comparison of the model's predictions with the experimental data shows that NO formation in the afterglow occurs via reactive quenching of multiple excited electronic levels of nitrogen molecule, N2\\ast , by O atoms. ) published in this volume, which focuses on the kinetic modelling of the experiments. This paper presents the results of the experiments.

  20. Peak experiences and the afterglow phenomenon: when and how do therapeutic effects of hallucinogens depend on psychedelic experiences?

    PubMed

    Majić, Tomislav; Schmidt, Timo T; Gallinat, Jürgen

    2015-03-01

    Interest in the therapeutic potential of psychedelic substances has recently resumed. During an early phase of human psychedelic research, their therapeutic application in different pathologies had been suggested, and the first evidence for efficacy was provided. The range of recent clinical applications of psychedelics spans from cluster headaches and obsessive-compulsive disorder to addiction and the treatment of fear and anxiety in patients suffering from terminal illness, indicating potentially different therapeutic mechanisms. A variety of approaches in psychotherapy emphasize subjective experiences, such as so-called peak experiences or afterglow phenomena, as differentially mediating therapeutic action. This review aims to re-evaluate earlier and recent concepts of how psychedelic substances may exert beneficial effects. After a short outline of neurophenomenological aspects, we discuss different approaches to how psychedelics are used in psychotherapy. Finally, we summarize evidence for the relationship between subjective experiences and therapeutic success. While the distinction between pharmacological and psychological action obviously cannot be clear-cut, they do appear to contribute differently from each other when their effects are compared with regard to pathologies.

  1. MAGNETICALLY DRIVEN WINDS FROM DIFFERENTIALLY ROTATING NEUTRON STARS AND X-RAY AFTERGLOWS OF SHORT GAMMA-RAY BURSTS

    SciTech Connect

    Siegel, Daniel M.; Ciolfi, Riccardo; Rezzolla, Luciano

    2014-04-10

    Besides being among the most promising sources of gravitational waves, merging neutron star binaries also represent a leading scenario to explain the phenomenology of short gamma-ray bursts (SGRBs). Recent observations have revealed a large subclass of SGRBs with roughly constant luminosity in their X-ray afterglows, lasting 10-10{sup 4} s. These features are generally taken as evidence of a long-lived central engine powered by the magnetic spin-down of a uniformly rotating, magnetized object. We propose a different scenario in which the central engine powering the X-ray emission is a differentially rotating hypermassive neutron star (HMNS) that launches a quasi-isotropic and baryon-loaded wind driven by the magnetic field, which is built-up through differential rotation. Our model is supported by long-term, three-dimensional, general-relativistic, and ideal magnetohydrodynamic simulations, showing that this isotropic emission is a very robust feature. For a given HMNS, the presence of a collimated component depends sensitively on the initial magnetic field geometry, while the stationary electromagnetic luminosity depends only on the magnetic energy initially stored in the system. We show that our model is compatible with the observed timescales and luminosities and express the latter in terms of a simple scaling relation.

  2. Long-lived Ar-Hg plasma in the afterglow of a high-current pulsed discharge

    SciTech Connect

    Sergeichev, K. F.; Lukina, N. A.; Fesenko, A. A.

    2013-02-15

    High-density (n > 10{sup 12} cm{sup -3}) argon-mercury plasma produced by a short (t {approx} 20 {mu}s) high-power pulsed discharge in argon with an admixture of mercury vapor at a discharge current of {approx}50 A, an argon pressure of {approx}4 mm Hg, and a mercury vapor pressure of {approx}10{sup -3} mm Hg was studied using optical spectroscopy and radio physics methods. It is found that the lifetime of this plasma after the end of the discharge pulse is up to 10{sup -2} s. It is shown that such an abnormally long lifetime of such an afterglow plasma, as compared to the plasma of an argon discharge without an admixture of mercury vapor, is related to the long residence time of atoms and ions of both argon and mercury in highly excited states due to chemi-ionization processes involving long-lived metastable argon ions. It is suggested that dissociative recombination of highly excited molecular ions of argon play an important role in the transfer of excitation to argon atoms and ions that are close to autoionization states.

  3. Short GRB 130603B: Discovery of a jet break in the optical and radio afterglows, and a mysterious late-time X-ray excess

    SciTech Connect

    Fong, W.; Berger, E.; Margutti, R.; Chornock, R.; Migliori, G.; Zauderer, B. A.; Lunnan, R.; Laskar, T.; Metzger, B. D.; Foley, R. J.; Desch, S. J.; Meech, K. J.; Sonnett, S.; Dickey, C.; Hedlund, A.; Harding, P.

    2014-01-10

    We present radio, optical/NIR, and X-ray observations of the afterglow of the short-duration Swift and Konus-Wind GRB 130603B, and uncover a break in the radio and optical bands at ≈0.5 day after the burst, best explained as a jet break with an inferred jet opening angle of ≈4°-8°. GRB 130603B is only the third short GRB with a radio afterglow detection to date, and represents the first time that a jet break has been evident in the radio band. We model the temporal evolution of the spectral energy distribution to determine the burst explosion properties and find an isotropic-equivalent kinetic energy of ≈(0.6-1.7) × 10{sup 51} erg and a circumburst density of ≈5 × 10{sup –3}-30 cm{sup –3}. From the inferred opening angle of GRB 130603B, we calculate beaming-corrected energies of E {sub γ} ≈ (0.5-2) × 10{sup 49} erg and E {sub K} ≈ (0.1-1.6) × 10{sup 49} erg. Along with previous measurements and lower limits we find a median opening angle of ≈10°. Using the all-sky observed rate of 10 Gpc{sup –3} yr{sup –1}, this implies a true short GRB rate of ≈20 yr{sup –1} within 200 Mpc, the Advanced LIGO/VIRGO sensitivity range for neutron star binary mergers. Finally, we uncover evidence for significant excess emission in the X-ray afterglow of GRB 130603B at ≳ 1 day and conclude that the additional energy component could be due to fall-back accretion or spin-down energy from a magnetar formed following the merger.

  4. Hubble space telescope observations of the afterglow, supernova, and host galaxy associated with the extremely bright GRB 130427A

    SciTech Connect

    Levan, A. J.; Tanvir, N. R.; Wiersema, K.; Fruchter, A. S.; Hounsell, R. A.; Graham, J.; Hjorth, J.; Fynbo, J. P. U.; Pian, E.; Mazzali, P.; Perley, D. A.; Cano, Z.; Cenko, S. B.; Kouveliotou, C.; Misra, K.

    2014-09-10

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst (GRB), GRB 130427A. At z = 0.34, this burst affords an excellent opportunity to study the supernova (SN) and host galaxy associated with an intrinsically extremely luminous burst (E {sub iso} > 10{sup 54} erg): more luminous than any previous GRB with a spectroscopically associated SN. We use the combination of the image quality, UV capability, and invariant point-spread function of HST to provide the best possible separation of the afterglow, host, and SN contributions to the observed light ∼17 rest-frame days after the burst, utilizing a host subtraction spectrum obtained one year later. Advanced Camera for Surveys grism observations show that the associated SN, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, v {sub ph} ∼ 15, 000 km s{sup –1}). The positions of the bluer features are better matched by the higher velocity SN 2010bh (v {sub ph} ∼ 30, 000 km s{sup –1}), but this SN is significantly fainter and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated ∼4 kpc from the nucleus of a moderately star forming (1 M {sub ☉} yr{sup –1}), possibly interacting disk galaxy. The absolute magnitude, physical size, and morphology of this galaxy, as well as the location of the GRB within it, are also strikingly similar to those of GRB 980425/SN 1998bw. The similarity of the SNe and environment from both the most luminous and least luminous GRBs suggests that broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  5. Hubble Space Telescope Observations of the Afterglow, Supernova and Host Galaxy Associated with the Extremely Bright GRB 130427A

    NASA Technical Reports Server (NTRS)

    Levan, A.J.; Tanvir, N. R.; Fruchter, A. S.; Hjorth, J.; Pian, E.; Mazzali, P.; Hounsell, R. A.; Perley, D. A.; Cano, Z.; Graham, J.; Cenko, S. B.; Fynbo, J. P. U.; Kouveliotou, C.; Pe'er, A.; Misra, K.; Wiersema, K.

    2014-01-01

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst, GRB 130427A. At z=0.34 this burst affords an excellent opportunity to study the supernova and host galaxy associated with an intrinsically extremely luminous burst (E(sub iso) greater than 10(exp 54) erg): more luminous than any previous GRB with a spectroscopically associated supernova. We use the combination of the image quality, UV capability and and invariant PSF of HST to provide the best possible separation of the afterglow, host and supernova contributions to the observed light approximately 17 rest-frame days after the burst utilising a host subtraction spectrum obtained 1 year later. Advanced Camera for Surveys (ACS) grism observations show that the associated supernova, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, vph approximately 15,000 kilometers per second). The positions of the bluer features are better matched by the higher velocity SN 2010bh (vph approximately 30,000 kilometers per second), but SN 2010bh (vph approximately 30,000 kilometers per second but this SN is significantly fainter, and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated approximately 4 kpc from the nucleus of a moderately star forming (1 Solar Mass yr(exp-1)), possibly interacting disc galaxy. The absolute magnitude, physical size and morphology of this galaxy, as well as the location of the GRB within it are also strikingly similar to those of GRB980425SN 1998bw. The similarity of supernovae and environment from both the most luminous and least luminous GRBs suggests broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  6. EARLY-TIME VLA OBSERVATIONS AND BROADBAND AFTERGLOW ANALYSIS OF THE FERMI/LAT DETECTED GRB 130907A

    SciTech Connect

    Veres, Péter; Corsi, Alessandra; Frail, Dale A.; Cenko, S. Bradley; Perley, Daniel A.

    2015-09-01

    We present multi-wavelength observations of the hyper-energetic gamma-ray burst (GRB) 130907A, a Swift-discovered burst with early radio observations starting at ≈4 hr after the γ-ray trigger. GRB 130907A was also detected by the Fermi/LAT instrument and at late times showed a strong spectral evolution in X-rays. We focus on the early-time radio observations, especially at >10 GHz, to attempt to identify reverse shock signatures. While our radio follow-up of GRB 130907A ranks among the earliest observations of a GRB with the Karl G. Jansky Very Large Array, we did not see an unambiguous signature of a reverse shock. While a model with both reverse and forward shock can correctly describe the observations, the data is not constraining enough to decide upon the presence of the reverse-shock component. We model the broadband data using a simple forward-shock synchrotron scenario with a transition from a wind environment to a constant density interstellar medium (ISM) in order to account for the observed features. Within the confines of this model, we also derive the underlying physical parameters of the fireball, which are within typical ranges except for the wind density parameter (A{sub *}), which is higher than those for bursts with wind-ISM transition, but typical for the general population of bursts. We note the importance of early-time radio observations of the afterglow (and of well-sampled light curves) for unambiguously identifying the potential contribution of the reverse shock.

  7. Hubble Space Telescope Observations of the Afterglow, Supernova, and Host Galaxy Associated with the Extremely Bright GRB 130427A

    NASA Astrophysics Data System (ADS)

    Levan, A. J.; Tanvir, N. R.; Fruchter, A. S.; Hjorth, J.; Pian, E.; Mazzali, P.; Hounsell, R. A.; Perley, D. A.; Cano, Z.; Graham, J.; Cenko, S. B.; Fynbo, J. P. U.; Kouveliotou, C.; Pe'er, A.; Misra, K.; Wiersema, K.

    2014-09-01

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst (GRB), GRB 130427A. At z = 0.34, this burst affords an excellent opportunity to study the supernova (SN) and host galaxy associated with an intrinsically extremely luminous burst (E iso > 1054 erg): more luminous than any previous GRB with a spectroscopically associated SN. We use the combination of the image quality, UV capability, and invariant point-spread function of HST to provide the best possible separation of the afterglow, host, and SN contributions to the observed light ~17 rest-frame days after the burst, utilizing a host subtraction spectrum obtained one year later. Advanced Camera for Surveys grism observations show that the associated SN, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, v ph ~ 15, 000 km s-1). The positions of the bluer features are better matched by the higher velocity SN 2010bh (v ph ~ 30, 000 km s-1), but this SN is significantly fainter and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated ~4 kpc from the nucleus of a moderately star forming (1 M ⊙ yr-1), possibly interacting disk galaxy. The absolute magnitude, physical size, and morphology of this galaxy, as well as the location of the GRB within it, are also strikingly similar to those of GRB 980425/SN 1998bw. The similarity of the SNe and environment from both the most luminous and least luminous GRBs suggests that broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  8. Characterizing a fast-response, low-afterglow liquid scintillator for neutron time-of-flight diagnostics in fast ignition experiments

    SciTech Connect

    Abe, Y. Hosoda, H.; Arikawa, Y.; Nagai, T.; Kojima, S.; Sakata, S.; Inoue, H.; Iwasa, Y.; Iwano, K.; Yamanoi, K.; Fujioka, S.; Nakai, M.; Sarukura, N.; Shiraga, H.; Norimatsu, T.; Azechi, H.

    2014-11-15

    The characteristics of oxygen-enriched liquid scintillators with very low afterglow are investigated and optimized for application to a single-hit neutron spectrometer for fast ignition experiments. It is found that 1,2,4-trimethylbenzene has better characteristics as a liquid scintillator solvent than the conventional solvent, p-xylene. In addition, a benzophenon-doped BBQ liquid scintillator is shown to demonstrate very rapid time response, and therefore has potential for further use in neutron diagnostics with fast time resolution.

  9. Intercrystalline distal-effect on the afterglow phenomenon in photoluminescent SrAl2O4:Ce(III), Ln nanotube growth

    NASA Astrophysics Data System (ADS)

    Khaled Zurba, Nadia; Bdikin, Igor; Kholkin, Andrei; Golberg, Dmitri; Ferreira, José M. F.

    2010-08-01

    We report a new method for the synthesis of photoluminescent SrAl2O4:Ce3 + , Dy3 + , Eu2 + nanotubes, PL-SNT:Ce(III), Ln, using solid-state reaction and post-annealing approach. This new optical nanotubular structure was characterized by HRTEM, SEM, AFM, EDX, steady-state and time-resolved PL spectroscopy. A series of f-f and f-d-transitions with light emission in structured bands peaking at 488 nm arising from the polymorphism of the host lattice was correlated with an intercrystalline distal-effect on the afterglow phenomenon.

  10. Note: Light output enhanced fast response and low afterglow {sup 6}Li glass scintillator as potential down-scattered neutron diagnostics for inertial confinement fusion

    SciTech Connect

    Arikawa, Yasunobu; Yamanoi, Kohei; Nagai, Takahiro; Watanabe, Kozue; Kouno, Masahiro; Sakai, Kohei; Nakazato, Tomoharu; Shimizu, Toshihiko; Cadatal, Marilou Raduban; Estacio, Elmer Surat; Sarukura, Nobuhiko; Nakai, Mitsuo; Norimatsu, Takayoshi; Azechi, Hiroshi; Murata, Takahiro; Fujino, Shigeru; Yoshida, Hideki; Izumi, Nobuhiko; Satoh, Nakahiro; Kan, Hirofumi

    2010-10-15

    The characteristics of an APLF80+3Ce scintillator are presented. Its sufficiently fast decay profile, low afterglow, and an improved light output compared to the recently developed APLF80+3Pr, were experimentally demonstrated. This scintillator material holds promise for applications in neutron imaging diagnostics at the energy regions of 0.27 MeV of DD fusion down-scattered neutron peak at the world's largest inertial confinement fusion facilities such as the National Ignition Facility and the Laser Megajoule.

  11. Optical light curve of GRB 121011A: a textbook for the onset of GRB afterglow in a mixture of ISM and wind-type medium

    NASA Astrophysics Data System (ADS)

    Xin, Li-Ping; Wei, Jian-Yan; Qiu, Yu-Lei; Deng, Jin-Song; Wang, Jing; Han, Xu-Hui

    2016-01-01

    We report the optical observations of GRB 121011A by the 0.8m TNT facility at Xinglong observatory, China. The light curve of the optical afterglow shows a smooth and featureless bump during the epoch of ˜130 s and ˜5000 s with a rising index of 1.57 ± 0.28 before the break time of 539 ± 44 s, and a decaying index of about 1.29 ± 0.07 up to the end of our observations. Moreover, the X-ray light curve decays in a single power-law with a slope of about 1.51 ± 0.03 observed by XRT onboard Swift from 100 s to about 10 000 s after the burst trigger. The featureless optical light curve could be understood as an onset process under the external-shock model. The typical frequency has been below or near the optical one before the deceleration time, and the cooling frequency is located between the optical and X-ray wavelengths. The external medium density has a transition from a mixed stage of ISM and wind-type medium before the peak time to the ISM at the later phase. The joint-analysis of X-ray and optical light curves shows that the emissions from both frequencies are consistent with the prediction of the standard afterglow model without any energy injections, indicating that the central engine has stopped its activity and does not restart anymore after the prompt phase.

  12. Investigation and Applications of In-Source Oxidation in Liquid Sampling-Atmospheric Pressure Afterglow Microplasma Ionization (LS-APAG) Source.

    PubMed

    Xie, Xiaobo; Wang, Zhenpeng; Li, Yafeng; Zhan, Lingpeng; Nie, Zongxiu

    2016-12-19

    A liquid sampling-atmospheric pressure afterglow microplasma ionization (LS-APAG) source is presented for the first time, which is embedded with both electrospray ionization (ESI) and atmospheric pressure afterglow microplasma ionization (APAG) techniques. This ion source is capable of analyzing compounds with diverse molecule weights and polarities. An unseparated mixture sample was detected as a proof-of-concept, giving complementary information (both polarities and non-polarities) with the two ionization modes. It should also be noted that molecular mass can be quickly identified by ESI with clean and simple spectra, while the structure can be directly studied using APAG with in-source oxidation. The ionization/oxidation mechanism and applications of the LS-APAG source have been further explored in the analysis of nonpolar alkanes and unsaturated fatty acids/esters. A unique [M + O - 3H](+) was observed in the case of individual alkanes (C5-C19) and complex hydrocarbons mixture under optimized conditions. Moreover, branched alkanes generated significant in-source fragments, which could be further applied to the discrimination of isomeric alkanes. The technique also facilitates facile determination of double bond positions in unsaturated fatty acids/esters due to diagnostic fragments (the acid/ester-containing aldehyde and acid oxidation products) generated by on-line ozonolysis in APAG mode. Finally, some examples of in situ APAG analysis by gas sampling and surface sampling were given as well. Graphical Abstract ᅟ.

  13. Gamma-ray Burst Afterglows as Probes of Environment and Blastwave Physics: Absorption by Host Galaxy Gas and Dust, Circumburst Media and the Distribution of P

    NASA Technical Reports Server (NTRS)

    Starling, R. L. C.; Wijers, R. a. M. J.; Curran, P.; Rol, E.; Wiersema, K.; Kouveliotou, C.; vanderHorst, A. J.

    2006-01-01

    We use a new approach to obtain limits on the absorbing columns towards a sample of 10 Gamma-ray Bursts observed by BeppoSAX from simultaneous fits to X-ray, optical and IR data, in counts space and including the effects of metallicity. For half the afterglows the best-fitting model to the SED includes SMC-like extinction (as opposed to LMC or MW) and in one LMC-like extinction, and in no cases is there a preference for MW-like extinction. Gas-to-dust ratios generally do not match those of the 3 standard and most well-known extinction models of SMC, LMC and MW, but tend to be higher. We compare the results from this method to those of previous works using other methods. We constrain the jet models for a subsample of the bursts by constraining the cooling break position and power law spectral slopes, allowing the injected electron energy index to be measured. We derive secure values of p from our spectral fits and comparison with the temporal optical and X-ray slopes for 4 afterglows. The mean of these single value, suggesting that either external factors such as circumburst medium play a strong role or that the microphysics is not identical for each GRB. For GRB 971214 we find that the circumburst medium has a wind-like density profile and the cooling frequency appears to be moving to higher frequencies.

  14. Functional near infrared-emitting Cr3+/Pr3+ co-doped zinc gallogermanate persistent luminescent nanoparticles with superlong afterglow for in vivo targeted bioimaging.

    PubMed

    Abdukayum, Abdukader; Chen, Jia-Tong; Zhao, Qiang; Yan, Xiu-Ping

    2013-09-25

    Near infrared (NIR)-emitting persistent luminescent nanoparticles (PLNPs) have great potential for in vivo bioimaging with the advantages of no need for in situ excitation, high signal-to-noise ratio, and deep tissue penetration. However, functional NIR-emitting PLNPs with long afterglow for long-term in vivo imaging are lacking. Here, we show the synthesis of NIR-emitting long-persistent luminescent nanoparticles (LPLNPs) Zn2.94Ga1.96Ge2O10:Cr(3+),Pr(3+) by a citrate sol-gel method in combination with a subsequent reducing atmosphere-free calcination. The persistent luminescence of the LPLNPs is significantly improved via codoping Pr(3+)/Cr(3+) and creating suitable Zn deficiency in zinc gallogermanate. The LPLNP powder exhibits bright NIR luminescence in the biological transparency window with a superlong afterglow time of over 15 days. A persistent energy transfer between host and Cr(3+) ion in the LPLNPs is observed and its mechanism is discussed. PEGylation greatly improves the biocompatibility and water solubility of the LPLNPs. Further bioconjugation with c(RGDyK) peptide makes the LPLNPs promising for long-term in vivo targeted tumor imaging with low toxicity.

  15. Strategies for Prompt Searches for GRB Afterglows: The Discovery of GRB 001011 Optical/Near-Infrared Counterpart Using Colour-Colour Selection

    NASA Technical Reports Server (NTRS)

    Gorosabel, J.; Fynbo, J. U.; Hjorth, J.; Wolf, C.; Andersen, M. I.; Pedersen, H.; Christensen, L.; Jensen, B. L.; Moller, P.; Afonso, J.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    We report the discovery of the optical and near-infrared counterpart to GRB 001011. The GRB 001011 error box determined by Beppo-SAX was simultaneously imaged in the near-infrared by the 3.58-m. New Technology Telescope and in the optical by the 1.54-m Danish Telescope - 8 hr after the gamma-ray event. We implement the colour-colour discrimination technique proposed by Rhoads (2001) and extend it using near-IR data as well. We present the results provided by an automatic colour-colour discrimination pipe-line developed to discern the different populations of objects present in the GRB 001011 error box. Our software revealed three candidates based on single-epoch images. Second-epoch observations carried out approx. 3.2 days after the burst revealed that the most likely candidate had faded thus identifying it with the counterpart to the GRB. In deep R-band images obtained 7 months after the burst a faint (R=25.38 plus or minus 0.25) elongated object, presumably the host galaxy of GRB 001011, was detected at the position of the afterglow. The GRB 001011 afterglow is the first discovered with the assistance of colour-colour diagram techniques. We discuss the advantages of using this method and its application to boxes determined by future missions.

  16. GRB 091208B: FIRST DETECTION OF THE OPTICAL POLARIZATION IN EARLY FORWARD SHOCK EMISSION OF A GAMMA-RAY BURST AFTERGLOW

    SciTech Connect

    Uehara, T.; Chiyonobu, S.; Fukazawa, Y.; Ikejiri, Y.; Itoh, R.; Komatsu, T.; Miyamoto, H.; Nagae, O.; Sakimoto, K.; Sasada, M.; Tanaka, H.; Yamanaka, M.; Toma, K.; Kawabata, K. S.; Mizuno, T.; Ohsugi, T.; Uemura, M.; Inoue, T.; Yamashita, T.; Nakaya, H.; and others

    2012-06-10

    We report that the optical polarization in the afterglow of GRB 091208B is measured at t = 149-706 s after the burst trigger, and the polarization degree is P = 10.4( {+-} 2.5%. The optical light curve at this time shows a power-law decay with index -0.75 {+-} 0.02, which is interpreted as the forward shock synchrotron emission, and thus this is the first detection of the early-time optical polarization in the forward shock (rather than that in the reverse shock reported by Steele et al.). This detection disfavors the afterglow model in which the magnetic fields in the emission region are random on the plasma skin depth scales, such as those amplified by the plasma instabilities, e.g., Weibel instability. We suggest that the fields are amplified by the magnetohydrodynamic instabilities, which would be tested by future observations of the temporal changes of the polarization degrees and angles for other bursts.

  17. A Correlation between the Intrinsic Brightness and Average Decay Rate of Gamma-Ray Burst X-Ray Afterglow Light Curves

    NASA Astrophysics Data System (ADS)

    Racusin, J. L.; Oates, S. R.; de Pasquale, M.; Kocevski, D.

    2016-07-01

    We present a correlation between the average temporal decay ({α }{{X},{avg},\\gt 200{{s}}}) and early-time luminosity ({L}{{X},200{{s}}}) of X-ray afterglows of gamma-ray bursts as observed by the Swift X-ray Telescope. Both quantities are measured relative to a rest-frame time of 200 s after the γ-ray trigger. The luminosity-average decay correlation does not depend on specific temporal behavior and contains one scale-independent quantity minimizing the role of selection effects. This is a complementary correlation to that discovered by Oates et al. in the optical light curves observed by the Swift Ultraviolet Optical Telescope. The correlation indicates that, on average, more luminous X-ray afterglows decay faster than less luminous ones, indicating some relative mechanism for energy dissipation. The X-ray and optical correlations are entirely consistent once corrections are applied and contamination is removed. We explore the possible biases introduced by different light-curve morphologies and observational selection effects, and how either geometrical effects or intrinsic properties of the central engine and jet could explain the observed correlation.

  18. Investigation and Applications of In-Source Oxidation in Liquid Sampling-Atmospheric Pressure Afterglow Microplasma Ionization (LS-APAG) Source

    NASA Astrophysics Data System (ADS)

    Xie, Xiaobo; Wang, Zhenpeng; Li, Yafeng; Zhan, Lingpeng; Nie, Zongxiu

    2016-12-01

    A liquid sampling-atmospheric pressure afterglow microplasma ionization (LS-APAG) source is presented for the first time, which is embedded with both electrospray ionization (ESI) and atmospheric pressure afterglow microplasma ionization (APAG) techniques. This ion source is capable of analyzing compounds with diverse molecule weights and polarities. An unseparated mixture sample was detected as a proof-of-concept, giving complementary information (both polarities and non-polarities) with the two ionization modes. It should also be noted that molecular mass can be quickly identified by ESI with clean and simple spectra, while the structure can be directly studied using APAG with in-source oxidation. The ionization/oxidation mechanism and applications of the LS-APAG source have been further explored in the analysis of nonpolar alkanes and unsaturated fatty acids/esters. A unique [M + O - 3H]+ was observed in the case of individual alkanes (C5-C19) and complex hydrocarbons mixture under optimized conditions. Moreover, branched alkanes generated significant in-source fragments, which could be further applied to the discrimination of isomeric alkanes. The technique also facilitates facile determination of double bond positions in unsaturated fatty acids/esters due to diagnostic fragments (the acid/ester-containing aldehyde and acid oxidation products) generated by on-line ozonolysis in APAG mode. Finally, some examples of in situ APAG analysis by gas sampling and surface sampling were given as well.

  19. Roles of doping ions in afterglow properties of blue CaAl2O4:Eu2+,Nd3+ phosphors

    NASA Astrophysics Data System (ADS)

    Wako, A. H.; Dejene, B. F.; Swart, H. C.

    2014-04-01

    Eu2+ doped and Nd3+ co-doped calcium aluminate (CaAl2O4:Eu2+,Nd3+) phosphor was prepared by a urea-nitrate solution combustion method at furnace temperatures as low as 500 °C. The produced CaAl2O4:Eu2+,Nd3+ powder was investigated in terms of phase composition, morphology and luminescence by X-Ray diffraction (XRD), Scanning Electron Microscope (SEM), Fourier Transform Infra Red spectroscopy (FTIR) and Photoluminescence (PL) techniques respectively. XRD analysis depicts a dominant monoclinic phase that indicates no change in the crystalline structure of the phosphor with varying concentration of Eu2+ and Nd3+. SEM results show agglomerates with non-uniform shapes and sizes with a number of irregular network structures having lots of voids and pores. The Energy Dispersive X-ray Spectroscopy (EDS) and (FTIR) spectra confirm the expected chemical components of the phosphor. PL measurements indicated one broadband excitation spectra from 200 to 300 nm centered around 240 nm corresponding to the crystal field splitting of the Eu2+ d-orbital and an emission spectrum in the blue region with a maximum on 440 nm. This is a strong indication that there was dominantly one luminescence center, Eu2+ which represents emission from transitions between the 4f7 ground state and the 4f6-5d1 excited state configuration. High concentrations of Eu2+ and Nd3+ generally reduce both intensity and lifetime of the phosphor powders. The optimized content of Eu2+ is 1 mol% and for Nd3+ is 1 mol% for the obtained phosphors with excellent optical properties. The phosphor also emits visible light at around 587 and 616 nm. Such emissions can be ascribed to the 5D0-7F1 and 5D0-7F2 intrinsic transition of Eu3+ respectively. The decay characteristics exhibit a significant rise in initial intensity with increasing Eu2+ doping concentration while the decay time increased with Nd3+ co-doping. The observed afterglow can be ascribed to the generation of suitable traps due to the presence of the Nd3

  20. UVES/VLT high resolution absorption spectroscopy of the GRB 080330 afterglow: a study of the GRB host galaxy and intervening absorbers

    NASA Astrophysics Data System (ADS)

    D'Elia, V.; Fiore, F.; Perna, R.; Krongold, Y.; Vergani, S. D.; Campana, S.; Covino, S.; D'Avanzo, P.; Fugazza, D.; Goldoni, P.; Guidorzi, C.; Meurs, E. J. A.; Norci, L.; Piranomonte, S.; Tagliaferri, G.; Ward, P.

    2009-08-01

    Aims: We study the gamma-ray burst (GRB) environment and intervening absorbers by analyzing the optical absorption features produced by gas surrounding the GRB or along its line of sight. Methods: We analyzed high resolution spectroscopic observations (R = 40 000, S/N = 3-6) of the optical afterglow of GRB 080330, taken with UVES at the VLT ~ 1.5 h after the GRB trigger. Results: The spectrum illustrates the complexity of the ISM of the GRB host galaxy at z = 1.51 which has at least four components in the main absorption system. We detect strong FeII, SiII, and NiII excited absorption lines associated with the bluemost component only. In addition to the host galaxy, at least two more absorbers lying along the line of sight to the afterglow have been detected in the redshift range 0.8 < z < 1.1, each exhibiting MgII absorption. For the bluemost component in the host galaxy, we derive information about its distance from the site of the GRB explosion. We do so by assuming that the excited absorption lines are produced by indirect UV pumping, and compare the data with a time dependent photo-excitation code. The distance of this component is found to be ˜ 280+40-50 pc, which is lower than found for other GRBs (1-6 kpc). We identify two additional MgII absorbers, one of them with a rest frame equivalent width larger than 1 Å. Conclusions: The distance between the GRB and the absorber measured in this paper confirms that the power of the GRB radiation can influence the conditions of the interstellar medium up to a distance of at least several hundred pc. For the intervening absorbers, we confirm the trend that on average one strong intervening system is found per afterglow, as has been noted in studies exhibiting an excess of strong MgII absorbers along GRB sightlines compared to quasars. Based on observations collected at the European Southern Observatory, ESO, the VLT/Kueyen telescope, Paranal, Chile, in the framework of programs 080.A-0398.

  1. GAMMA-RAY BURST AFTERGLOW LIGHT CURVES FROM A LORENTZ-BOOSTED SIMULATION FRAME AND THE SHAPE OF THE JET BREAK

    SciTech Connect

    Van Eerten, Hendrik; MacFadyen, Andrew

    2013-04-20

    The early stages of decelerating gamma-ray burst (GRB) afterglow jets have been notoriously difficult to resolve numerically using two-dimensional hydrodynamical simulations even at very high resolution, due to the extreme thinness of the blast wave and high outflow Lorentz factors. However, these resolution issues can be avoided by performing the simulations in a boosted frame, which makes it possible to calculate afterglow light curves from numerically computed flows in sufficient detail to accurately quantify the shape of the jet break and the post-break steepening of the light curve. Here, we study afterglow jet breaks for jets with opening angles of 0.05, 0.1, and 0.2 radians decelerating in a surrounding medium of constant density, observed at various angles ranging from on-axis to the edge of the jet. A single set of scale-invariant functions describing the time evolution of afterglow synchrotron spectral break frequencies and peak flux, depending only on jet opening angle and observer angle, are all that is needed to reconstruct light curves for arbitrary explosion energy, circumburst density and synchrotron particle distribution power law slope p. These functions are presented in the paper. Their time evolutions change directly following the jet break, although an earlier reported temporary post-break steepening of the cooling break is found to have been resolution-induced. We compare synthetic light curves to fit functions using sharp power law breaks as well as smooth power law transitions. We confirm our earlier finding that the measured jet break time is very sensitive to the angle of the observer and can be postponed significantly. We find that the difference in temporal indices across the jet break is larger than theoretically anticipated and is about -(0.5 + 0.5p) below the cooling break and about -(0.25 + 0.5p) above the cooling break, both leading to post-break slopes of roughly about 0.25 - 1.3p, although different observer angles, jet opening

  2. LOW-RESOLUTION SPECTROSCOPY OF GAMMA-RAY BURST OPTICAL AFTERGLOWS: BIASES IN THE SWIFT SAMPLE AND CHARACTERIZATION OF THE ABSORBERS

    SciTech Connect

    Fynbo, J. P. U.; Malesani, D.; Vreeswijk, P. M.; Hjorth, J.; Sollerman, J.; Thoene, C. C.; Jakobsson, P.; Bjoernsson, G.; De Cia, A.; Prochaska, J. X.; Nardini, M.; Chen, H.-W.; Bloom, J. S.; Castro-Tirado, A. J.; Gorosabel, J.; Christensen, L.; Fruchter, A. S.

    2009-12-01

    We present a sample of 77 optical afterglows (OAs) of Swift detected gamma-ray bursts (GRBs) for which spectroscopic follow-up observations have been secured. Our first objective is to measure the redshifts of the bursts. For the majority (90%) of the afterglows, the redshifts have been determined from the spectra. We provide line lists and equivalent widths (EWs) for all detected lines redward of Ly{alpha} covered by the spectra. In addition to the GRB absorption systems, these lists include line strengths for a total of 33 intervening absorption systems. We discuss to what extent the current sample of Swift bursts with OA spectroscopy is a biased subsample of all Swift detected GRBs. For that purpose we define an X-ray-selected statistical sample of Swift bursts with optimal conditions for ground-based follow-up from the period 2005 March to 2008 September; 146 bursts fulfill our sample criteria. We derive the redshift distribution for the statistical (X-ray selected) sample and conclude that less than 18% of Swift bursts can be at z > 7. We compare the high-energy properties (e.g., {gamma}-ray (15-350 keV) fluence and duration, X-ray flux, and excess absorption) for three subsamples of bursts in the statistical sample: (1) bursts with redshifts measured from OA spectroscopy; (2) bursts with detected optical and/or near-IR afterglow, but no afterglow-based redshift; and (3) bursts with no detection of the OA. The bursts in group (1) have slightly higher {gamma}-ray fluences and higher X-ray fluxes and significantly less excess X-ray absorption than bursts in the other two groups. In addition, the fractions of dark bursts, defined as bursts with an optical to X-ray slope {beta}{sub OX} < 0.5, is 14% in group (1), 38% in group (2), and >39% in group (3). For the full sample, the dark burst fraction is constrained to be in the range 25%-42%. From this we conclude that the sample of GRBs with OA spectroscopy is not representative for all Swift bursts, most likely due

  3. Drop-on-demand sample introduction system coupled with the flowing atmospheric-pressure afterglow for direct molecular analysis of complex liquid microvolume samples.

    PubMed

    Schaper, J Niklas; Pfeuffer, Kevin P; Shelley, Jacob T; Bings, Nicolas H; Hieftje, Gary M

    2012-11-06

    One of the fastest developing fields in analytical spectrochemistry in recent years is ambient desorption/ionization mass spectrometry (ADI-MS). This burgeoning interest has been due to the demonstrated advantages of the method: simple mass spectra, little or no sample preparation, and applicability to samples in the solid, liquid, or gaseous state. One such ADI-MS source, the flowing atmospheric-pressure afterglow (FAPA), is capable of direct analysis of solids just by aiming the source at the solid surface and sampling the produced ions into a mass spectrometer. However, direct introduction of significant volumes of liquid samples into this source has not been possible, as solvent loads can quench the afterglow and, thus, the formation of reagent ions. As a result, the analysis of liquid samples is preferably carried out by analyzing dried residues or by desorbing small amounts of liquid samples directly from the liquid surface. In the former case, reproducibility of sample introduction is crucial if quantitative results are desired. In the present study, introduction of liquid samples as very small droplets helps overcome the issues of sample positioning and reduced levels of solvent intake. A recently developed "drop-on-demand" (DOD) aerosol generator is capable of reproducibly producing very small volumes of liquid (∼17 pL). In this paper, the coupling of FAPA-MS and DOD is reported and applications are suggested. Analytes representing different classes of substances were tested and limits of detections were determined. Matrix tolerance was investigated for drugs of abuse and their metabolites by analyzing raw urine samples and quantification without the use of internal standards. Limits of detection below 2 μg/mL, without sample pretreatment, were obtained.

  4. Observational Signatures of High-Energy Emission during the Shallow Decay Phase of Gamma-Ray Burst X-Ray Afterglows

    NASA Astrophysics Data System (ADS)

    Yu, Y. W.; Liu, X. W.; Dai, Z. G.

    2007-12-01

    The widely existing shallow decay phase of the X-ray afterglows of gamma-ray bursts (GRBs) is generally accepted to be due to long-lasting energy injection. The outflows carrying the injecting energy, based on the component that is dominant in energy, fall into two possible types: baryon-dominated and lepton-dominated ones. The former type of outflow could be ejecta that is ejected during the prompt phase of a GRB and consists of a series of baryonic shells with a distribution of Lorentz factors, and the latter type could be an electron-positron pair wind that is driven by the postburst central engine. We here provide a unified description for the dynamics of fireballs based on these two types of energy injection and calculate the corresponding high-energy photon emission by considering synchrotron radiation and inverse Compton scattering (including synchrotron self-Compton and combined inverse Compton) of electrons. We find that, in the two energy-injection models, there is a plateau (even a hump) in high-energy light curves during the X-ray shallow decay phase. In particular, a considerable fraction of the injecting energy in the lepton-dominated model can be shared by the long-lasting reverse shock since it is relativistic. Furthermore, almost all of the energy of the reverse shock is carried by leptons, and thus, the inverse Compton emission is enhanced dramatically. Therefore, this model predicts more significant high-energy afterglow emission than the baryon-dominated model. We argue that these observational signatures would be used to discriminate between different energy-injection models in the upcoming Gamma-Ray Large Area Space Telescope (GLAST) era.

  5. Towards depth profiling of organic aerosols in real time using aerosol flowing atmospheric-pressure afterglow mass spectrometry (AeroFAPA-MS)

    NASA Astrophysics Data System (ADS)

    Brüggemann, Martin; Hoffmann, Thorsten

    2014-05-01

    Organic aerosol accounts for a substantial fraction of tropospheric aerosol and has implications on the earth's climate and human health. However, the characterization of its chemical composition and transformations remain a major challenge and is still connected to large uncertainties (IPCC, 2013). Recent measurements revealed that organic aerosol particles may reside in an amorphous or semi-solid phase state which impedes the diffusion within the particles (Virtanen et al., 2010; Shiraiwa et al., 2011). This means that reaction products which are formed on the surface of a particle, e.g. by OH, NO3 or ozone chemistry, cannot diffuse into the particle's core and remain at the surface. Eventually, this leads to particles with a core/shell structure. In the particles' cores the initial compounds are preserved whereas the shells contain mainly the oxidation products. By analyzing the particles' cores and shells separately, thus, it is possible to obtain valuable information on the formation and evolution of the aerosols' particle and gas phase. Here we present the development of the aerosol flowing atmospheric-pressure afterglow (AeroFAPA) technique which allows the mass spectrometric analysis of organic aerosols in real time. The AeroFAPA is an ion source based on a helium glow discharge at atmospheric pressure. The plasma produces excited helium species and primary reagent ions which are transferred into the afterglow region where the ionization of the analytes takes place. Due to temperatures of only 80 ° C to 150 ° C and ambient pressure in the afterglow region, the ionization is very soft and almost no fragmentation of organic molecules is observed. Thus, the obtained mass spectra are easy to interpret and no extensive data analysis procedure is necessary. Additionally, first results of a combination of the AeroFAPA-MS with a scanning mobility particle sizer (SMPS) suggest that it is not only possible to analyze the entire particle phase but rather that a

  6. Real-time analysis of ambient organic aerosols using aerosol flowing atmospheric-pressure afterglow mass spectrometry (AeroFAPA-MS)

    NASA Astrophysics Data System (ADS)

    Brüggemann, Martin; Karu, Einar; Stelzer, Torsten; Hoffmann, Thorsten

    2015-04-01

    Organic aerosol accounts for a major fraction of atmospheric aerosols and has implications on the earth's climate and human health. However, due to the chemical complexity its measurement remains a major challenge for analytical instrumentation.1 Here, we present the development, characterization and application of a new soft ionization technique that allows mass spectrometric real-time detection of organic compounds in ambient aerosols. The aerosol flowing atmospheric-pressure afterglow (AeroFAPA) ion source utilizes a helium glow discharge plasma to produce excited helium species and primary reagent ions. Ionization of the analytes occurs in the afterglow region after thermal desorption and results mainly in intact molecular ions, facilitating the interpretation of the acquired mass spectra. In the past, similar approaches were used to detect pesticides, explosives or illicit drugs on a variety of surfaces.2,3 In contrast, the AeroFAPA source operates 'online' and allows the detection of organic compounds in aerosols without a prior precipitation or sampling step. To our knowledge, this is the first application of an atmospheric-pressure glow discharge ionization technique to ambient aerosol samples. We illustrate that changes in aerosol composition and concentration are detected on the time scale of seconds and in the ng-m-3 range. Additionally, the successful application of AeroFAPA-MS during a field study in a mixed forest region in Central Europe is presented. Several oxidation products of monoterpenes were clearly identified using the possibility to perform tandem MS experiments. The acquired data are in agreement with previous studies and demonstrate that AeroFAPA-MS is a suitable tool for organic aerosol analysis. Furthermore, these results reveal the potential of this technique to enable new insights into aerosol formation, growth and transformation in the atmosphere. References: 1) IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The

  7. Simulations of Gamma-Ray Burst Jets in a Stratified External Medium: Dynamics, Afterglow Light Curves, Jet Breaks, and Radio Calorimetry

    NASA Astrophysics Data System (ADS)

    De Colle, Fabio; Ramirez-Ruiz, Enrico; Granot, Jonathan; Lopez-Camara, Diego

    2012-05-01

    The dynamics of gamma-ray burst (GRB) jets during the afterglow phase is most reliably and accurately modeled using hydrodynamic simulations. All published simulations so far, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here, we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with ρextvpropr -k for k = 0, 1, 2. The simulations are performed in two dimensions using the special relativistic version of the Mezcal code. Common to all calculations is the initiation of the GRB jet as a conical wedge of half-opening angle θ0 = 0.2 whose radial profile is taken from the self-similar Blandford-McKee solution. The dynamics for stratified external media (k = 1, 2) are broadly similar to those derived for expansion into a uniform external medium (k = 0). The jet half-opening angle is observed to start increasing logarithmically with time (or radius) once the Lorentz factor Γ drops below θ-1 0. For larger k values, however, the lateral expansion is faster at early times (when Γ > θ-1 0) and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timescales. We find that, contrary to analytic expectations, there is a reasonably sharp jet break in the light curve for k = 2 (a wind-like external medium), although the shape of the break is affected more by the viewing angle (for θobs <= θ0) than by the slope of the external density profile (for 0 <= k <= 2). Steeper density profiles (i.e., increasing k values) are found to produce more gradual jet breaks while larger viewing angles cause smoother and later appearing jet breaks. The counterjet becomes visible as it becomes sub-relativistic, and for k = 0 this results in a clear bump-like feature in the light curve. However, for larger k values the jet decelerates more

  8. CONSTRAINING GAMMA-RAY BURST INITIAL LORENTZ FACTOR WITH THE AFTERGLOW ONSET FEATURE AND DISCOVERY OF A TIGHT {Gamma}{sub 0}-E{sub {gamma},iso} CORRELATION

    SciTech Connect

    Liang Enwei; Yi Shuangxi; Lue Houjun; Zhang Jin; Zhang Binbin; Zhang Bing E-mail: zhang@physics.unlv.ed

    2010-12-20

    The onset of gamma-ray burst (GRB) afterglow is characterized by a smooth bump in the early afterglow light curve as the GRB fireball is decelerated by the circumburst medium. We extensively search for GRBs with such an onset feature in their optical and X-ray light curves from the literature and from the catalog established with the Swift/XRT. Twenty optically selected GRBs and 12 X-ray-selected GRBs are obtained, among which 17 optically selected and 2 X-ray-selected GRBs have redshift measurements. We fit these light curves with a smooth broken power law and measure the width (w), rising timescale (t{sub r}), and decaying timescale (t{sub d}) at full width at half-maximum. Strong mutual correlations among these timescales and with the peak time (t{sub p}) are found. The ratio t{sub r}/t{sub d} is almost universal among bursts, but the ratio t{sub r}/t{sub p} varies from 0.3 to {approx}1. The optical peak luminosity in the R band (L{sub R,p}) is anti-correlated with t{sub p} and w in the burst frame, indicating a dimmer and broader bump peaking at a later time. The isotropic prompt gamma-ray energy (E{sub {gamma},iso}) is also tightly correlated with L{sub R,p} and t{sub p} in the burst frame. Assuming that the bumps signal the deceleration of the GRB fireballs in a constant density medium, we calculate the initial Lorentz factor ({Gamma}{sub 0}) and the deceleration radius (R{sub d}) of the GRBs with redshift measurements. The derived {Gamma}{sub 0} is typically a few hundreds, and the deceleration radius is R{sub dec} {approx} 2 x 10{sup 17} cm. More intriguingly, a tight correlation between {Gamma}{sub 0} and E{sub {gamma},iso} is found, namely {Gamma}{sub 0} {approx_equal} 182(E{sub {gamma},iso}/10{sup 52} erg){sup 0.25}. This correlation also applies to the small sample of GRBs which show the signature of the afterglow onset in their X-ray afterglow, and to two bursts (GRBs 990123 and 080319B) whose early optical emission is dominated by a reverse shock. The

  9. The 80 Ms follow-up of the X-ray afterglow of GRB 130427A challenges the standard forward shock model

    NASA Astrophysics Data System (ADS)

    De Pasquale, M.; Page, M. J.; Kann, D. A.; Oates, S. R.; Schulze, S.; Zhang, B.; Cano, Z.; Gendre, B.; Malesani, D.; Rossi, A.; Troja, E.; Piro, L.; Boër, M.; Stratta, G.; Gehrels, N.

    2016-10-01

    GRB 130427A was the brightest gamma-ray burst detected in the last 30 yr. With an equivalent isotropic energy output of 8.5 × 1053 erg and redshift z = 0.34, it uniquely combined very high energetics with a relative proximity to Earth. As a consequence, its X-ray afterglow has been detected by sensitive X-ray observatories such as XMM-Newton and Chandra for a record-breaking baseline longer than 80 million seconds. We present the X-ray light curve of this event over such an interval. The light curve shows a simple power-law decay with a slope α = 1.309 ± 0.007 over more than three decades in time (47 ks-83 Ms). We discuss the consequences of this result for a few models proposed so far to interpret GRB 130427A, and more in general the significance of this outcome in the context of the standard forward shock model. We find that this model has difficulty in explaining our data, in both cases of constant density and stellar-wind circumburst media, and requires far-fetched values for the physical parameters involved.

  10. [Effect of different excitation monitoring wavelengths on emission spectrum of red long afterglow phosphor Sr3Al2O6 : Eu2+, Dy3+].

    PubMed

    Cui, Cai-e; Li, Jian; Huang, Ping; Liang, Li-ping; Wu, Yin-lan

    2012-01-01

    The Eu2+ and Dy3+ ion co-doped Sr3Al2O6 phosphor powders with long afterglow were prepared with high temperature solid-state reaction. The phase and the spectra properties of the material were characterized by X-ray diffraction (XRD) and fluorescence spectrophotometer. It was found that the sample is composed of pure Sr3Al2O6 phase. Furthermore, the emission peak of 537 nm under 360 nm excitation and that of 590 nm excited by 468 nm-light were obtained, respectively, and it is more interesting that the emission peaks were at 537 and 590 nm under 394 nm excitation. The effects of different excitation wavelengths on the emission spectrum were explained reasonably by the effect of nephelauxetic effect and crystal field. It revealed that the two types of luminescence with different color were caused by the differences of the center of gravity of the 5d excited state energy level and the split range of 5d energy level.

  11. Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. II. The Distribution of rho and Structure of the Circumburst Medium

    NASA Technical Reports Server (NTRS)

    Starling, R. L. C.; vanderHorst, A. J.; Rol, E.; Wijers, R. A. M. J.; Kouveliotou, C.; Wiersema, K.; Curran, P. A.; Weltervrede, P.

    2008-01-01

    We constrain blast wave parameters and the circumburst media ofa subsample of 10 BeppoSAX gamma-ray bursts (GRBs). For this sample we derive the values of the injected electron energy distribution index, p, and the density structure index of the circumburst medium, k, from simultaneous spectral fits to their X-ray, optical, and NIR afterglow data. The spectral fits have been done in count space and include the effects ofmetallicity, and are compared with the previously reported optical and X-ray temporal behavior. Using the blast wave model and some assumptions which include on-axis viewing and standard jet structure, constant blast wave energy, and no evolution of the microphysical parameters, we find a mean value ofp for the sample as a whole of 9.... oa -0.003.0" 2 a_ statistical analysis of the distribution demonstrates that the p-values in this sample are inconsistent with a single universal value forp at the 3 _ level or greater, which has significant implications for particle acceleration models. This approach provides us with a measured distribution ofcircumburst density structures rather than considering only the cases of k ----0 (homogeneous) and k - 2 (windlike). We find five GRBs for which k can be well constrained, and in four of these cases the circumburst medium is clearly windlike. The fifth source has a value of 0 < k < 1, consistent with a homogeneous circumburst medium.

  12. Gamma-Ray Burst Afterglows as Probes of Environment and Blastwave Physics II: The Distribution of p and Structure of the Circumburst Medium

    NASA Technical Reports Server (NTRS)

    Starling, R. L. C.; vanderHorst, A. J.; Rol, E.; Wijers, R. A. M. J.; Kouveliotou, C.; Wiersema, K.; Curran, P. A.; Weltevrede, P.

    2007-01-01

    We constrain blastwave parameters and the circumburst media of a subsample of BeppoSAX Gamma-Ray Bursts. For this sample we derive the values of the injected electron energy distribution index, p, and the density structure index of the circumburst medium, k, from simultaneous spectral fits to their X-ray, optical and nIR afterglow data. The spectral fits have been done in count space and include the effects of metallicity, and are compared with the previously reported optical and X-ray temporal behaviour. Assuming the fireball model, we can find a mean value of p for the sample as a whole of 2.035. A statistical analysis Of the distribution demonstrates that the p values in this sample are inconsistent with a single universal value for p at the 3sigma level or greater. This approach provides us with a measured distribution of circumburst density structures rather than considering only the cases of k = 0 (homogeneous) and k = 2 (wind-like). We find five GRBs for which k can be well constrained, and in four of these cases the circumburst medium is clearly wind-like. The fifth source has a value of 0 less than or equal to k less than or equal to 1, consistent with a homogeneous circumburst medium.

  13. Enhanced performance of cadmium selenide quantum dot-sensitized solar cells by incorporating long afterglow europium, dysprosium co-doped strontium aluminate phosphors.

    PubMed

    Sun, Hengchao; Pan, Likun; Piao, Xianqing; Sun, Zhuo

    2014-02-15

    CdSe quantum dot-sensitized solar cells based on an efficient bifunctional structured layer composed of long afterglow SrAl2O4:Eu,Dy phosphors on top of a transparent layer of nanocrystalline TiO2 were fabricated and their photovoltaic performances were investigated. The results show that a high power conversion efficiency of 1.22% is achieved for the cell with SrAl2O4:Eu,Dy at one sun illumination (AM 1.5 G, 100 mW cm(-2)), which is an increase of 48% compared to the cell without SrAl2O4:Eu,Dy (0.82%). After one sun illumination for 1 min and subsequent turn off of the light source, the cell with SrAl2O4:Eu,Dy still shows an efficiency of 0.04% under dark condition due to the irradiation by the long persistent light from SrAl2O4:Eu,Dy. The present strategy should provide a possibility to fulfill the operation of solar cells even in the dark.

  14. Towards understanding magnetic field generation in relativistic shocks with GRB afterglow observations and the GRB radiation mechanism with photospheric simulations and the X-ray flare radiation mechanism

    NASA Astrophysics Data System (ADS)

    Santana, Rodolfo

    2015-12-01

    In this thesis, we present three projects on open questions in the Gammaray Burst (GRB) field. In the first project, we used X-ray and optical observations to determine the amount of amplification of the ISM magnetic field needed to explain the GRB afterglow observations. We determined that mild amplification is required, at a level stronger than shock-compression but weaker than predicted by the Weibel mechanism. In the second project, we present a Monte Carlo code we wrote from scratch to perform realistic simulations of the photospheric process, one of the mechanisms considered to explain the GRB gamma-ray emission. We determined that photospheric emission can explain the GRB gamma-ray spectrum above the peak-energy if the photons are taken to have a temperature much smaller than the electron temperature and if the interactions between photons and electrons take place at a large optical depth. In the third project, we used multi-wavelength observations to constrain the X-ray flare radiation mechanism. We determined that synchrotron from a Poynting jet and the Photospheric process are the best candidates to explain the X-ray flare observations.

  15. Flowing Afterglow Studies of Temperature Dependencies for Electron Dissociative Recombination of HCNH+, CH3CNH+ and CH3CH2CNH+ and Their Symmetrical Proton Bound Dimers

    NASA Astrophysics Data System (ADS)

    McLain, J. L.; Adams, N. G.

    2009-12-01

    A study has been made using a variable temperature flowing afterglow Langmuir probe technique (VT-FALP) to determine the equilibrium temperature dependencies of the dissociative electron-ion recombination of the protonated cyanide ions (RCNH+, where R = H, CH3 and C2H5) and their symmetrical proton bound dimers (RCNH+NCR). The power law temperature dependencies of the recombination coefficients, αe, over the temperature range 180 to 600 K for the protonated ions are αe(T)(cm3s-1) = 3.5±0.5×10-7 (300/T)1.38 for HCNH+, αe(T)= 3.4±0.5×10-7 (300/T)1.03 for CH3CNH+, and αe(T)= 4.6×10-7(300/T)0.81 for CH3CH2CNH+. The equivalent values for the proton bound dimers are αe(T)(cm3s-1) = 2.4±0.4×10-6(300/T)0.5 for (HCN)2H+, αe(T)= 2.8±0.4×10-6(300/T)0.5 for (CH3CN)2H+, and αe(T)= 2.3±0.3×10-6(300/T)0.5 for (CH3CH2CN)2H+. The relevance of these data to molecular synthesis in the Titan ionosphere are discussed.

  16. Flowing afterglow studies of temperature dependencies for electron dissociative recombination of HCNH +, CH 3CNH + and CH 3CH 2CNH + and their symmetrical proton-bound dimers

    NASA Astrophysics Data System (ADS)

    McLain, J. L.; Adams, N. G.

    2009-11-01

    A study has been made using a variable temperature flowing afterglow Langmuir probe technique (VT-FALP) to determine the equilibrium temperature dependencies of the dissociative electron-ion recombination of the protonated cyanide ions (RCNH +, where R=H, CH 3 and C 2H 5) and their symmetrical proton-bound dimers (RCNH +NCR). The power law temperature dependencies of the recombination coefficients, αe, over the temperature range 180 to 600 K for the protonated ions are αe( T)(cm 3 s -1)=3.5±0.5×10 -7 (300/ T) 1.38 for HCNH +, αe( T)=3.4±0.5×10 -7 (300/ T) 1.03 for CH 3CNH +, and αe( T)=4.6±0.7×10 -7 (300/ T) 0.81 for CH 3CH 2CNH +. The equivalent values for the proton-bound dimers are αe( T)(cm 3 s -1)=2.4±0.4×10 -6(300/ T) 0.5 for (HCN) 2H + to αe( T)=2.8±0.4×10 -6(300/ T) 0.5 for (CH 3CN) 2H +, and αe( T)=2.3±0.3×10 -6(300/ T) 0.5 for (CH 3CH 2CN) 2H +. The relevance of these data to molecular synthesis in the interstellar medium and the Titan ionosphere are discussed.

  17. VLT/X-Shooter spectroscopy of the afterglow of the Swift GRB 130606A. Chemical abundances and reionisation at z ~ 6

    NASA Astrophysics Data System (ADS)

    Hartoog, O. E.; Malesani, D.; Fynbo, J. P. U.; Goto, T.; Krühler, T.; Vreeswijk, P. M.; De Cia, A.; Xu, D.; Møller, P.; Covino, S.; D'Elia, V.; Flores, H.; Goldoni, P.; Hjorth, J.; Jakobsson, P.; Krogager, J.-K.; Kaper, L.; Ledoux, C.; Levan, A. J.; Milvang-Jensen, B.; Sollerman, J.; Sparre, M.; Tagliaferri, G.; Tanvir, N. R.; de Ugarte Postigo, A.; Vergani, S. D.; Wiersema, K.; Datson, J.; Salinas, R.; Mikkelsen, K.; Aghanim, N.

    2015-08-01

    Context. The reionisation of the Universe is a process that is thought to have ended around z ~ 6, as inferred from spectroscopy of distant bright background sources, such as quasars (QSO) and gamma-ray burst (GRB) afterglows. Furthermore, spectroscopy of a GRB afterglow provides insight in its host galaxy, which is often too dim and distant to study otherwise. Aims: For the Swift GRB 130606A at z = 5.913 we have obtained a high S/N spectrum covering the full optical and near-IR wavelength region at intermediate spectral resolution with VLT/X-Shooter. We aim to measure the degree of ionisation of the intergalactic medium (IGM) between z = 5.02-5.84 and to study the chemical abundance pattern and dust content of its host galaxy. Methods: We estimated the UV continuum of the GRB afterglow using a power-law extrapolation, then measured the flux decrement due to absorption at Lyα,β, and γ wavelength regions. Furthermore, we fitted the shape of the red damping wing of Lyα. The hydrogen and metal absorption lines formed in the host galaxy were fitted with Voigt profiles to obtain column densities. We investigated whether ionisation corrections needed to be applied. Results: Our measurements of the Lyα-forest optical depth are consistent with previous measurements of QSOs, but have a much smaller uncertainty. The analysis of the red damping wing yields a neutral fraction xH i< 0.05 (3σ). We obtain column density measurements of H, Al, Si, and Fe; for C, O, S and Ni we obtain limits. The ionisation due to the GRB is estimated to be negligible (corrections <0.03 dex), but larger corrections may apply due to the pre-existing radiation field (up to 0.4 dex based on sub-DLA studies). Assuming that [ Si/Fe ] = +0.79 ± 0.13 is due to dust depletion, the dust-to-metal ratio is similar to the Galactic value. Conclusions: Our measurements confirm that the Universe is already predominantly ionised over the redshift range probed in this work, but was slightly more neutral at z

  18. A burst in a wind bubble and the impact on baryonic ejecta: high-energy gamma-ray flashes and afterglows from fast radio bursts and pulsar-driven supernova remnants

    NASA Astrophysics Data System (ADS)

    Murase, Kohta; Kashiyama, Kazumi; Mészáros, Peter

    2016-09-01

    Tenuous wind bubbles, which are formed by the spin-down activity of central compact remnants, are relevant in some models of fast radio bursts (FRBs) and superluminous supernovae (SNe). We study their high-energy signatures, focusing on the role of pair-enriched bubbles produced by young magnetars, rapidly rotating neutron stars, and magnetized white dwarfs. (i) First, we study the nebular properties and the conditions allowing for escape of high-energy gamma-rays and radio waves, showing that their escape is possible for nebulae with ages of ≳10-100 yr. In the rapidly rotating neutron star scenario, we find that radio emission from the quasi-steady nebula itself may be bright enough to be detected especially at sub-mm frequencies, which is relevant as a possible counterpart of pulsar-driven SNe and FRBs. (ii) Secondly, we consider the fate of bursting emission in the nebulae. We suggest that an impulsive burst may lead to a highly relativistic flow, which would interact with the nebula. If the shocked nebula is still relativistic, pre-existing non-thermal particles in the nebula can be significantly boosted by the forward shock, leading to short-duration (maybe millisecond or longer) high-energy gamma-ray flashes. Possible dissipation at the reverse shock may also lead to gamma-ray emission. (iii) After such flares, interactions with the baryonic ejecta may lead to afterglow emission with a duration of days to weeks. In the magnetar scenario, this burst-in-bubble model leads to the expectation that nearby (≲10-100 Mpc) high-energy gamma-ray flashes may be detected by the High-Altitude Water Cherenkov Observatory and the Cherenkov Telescope Array, and the subsequent afterglow emission may be seen by radio telescopes such as the Very Large Array. (iv) Finally, we discuss several implications specific to FRBs, including constraints on the emission regions and limits on soft gamma-ray counterparts.

  19. Flowing afterglow studies of the electron recombination of protonated cyanides (RCN)H+ and their proton-bound dimer ions (RCN)2H+ where R is H, CH3, and CH3CH2

    NASA Astrophysics Data System (ADS)

    McLain, J. L.; Molek, C. D.; , D. Osborne, Jr.; Adams, N. G.

    2009-05-01

    A study has been made of the electron-ion dissociative recombination of the protonated cyanides (RCNH+, R = H, CH3, C2H5) and their proton-bound dimers (RCN)2H+ at 300 K. This has been accomplished with the flowing afterglow technique using an electrostatic Langmuir probe to determine the electron density decay along the flow tube. For the protonated species, the recombination coefficients, [alpha]e(cm3 s-1), are (3.6 +/- 0.5) × 10-7, (3.4 +/- 0.5) × 10-7, (4.6 +/- 0.7) × 10-7 for R = H, CH3, C2H5, respectively. For the proton-bound dimers, the [alpha]e are substantially greater being (2.4 +/- 0.4) × 10-6, (2.8 +/- 0.4) × 10-6, (2.3 +/- 0.3) × 10-6 for R = H, CH3, C2H5, respectively. Fitting of the electron density decay data to a simple model has shown that the rate coefficients for the three-body association of RCNH+ with RCN are very large being (2.0 +/- 0.5) × 10-26 cm6 s-1. The significance of these data to the Titan ionosphere is discussed.

  20. The quest for short GRB radio afterglows

    NASA Astrophysics Data System (ADS)

    Burlon, Davide; Gaensler, Bryan; Murphy, Tara; Hancock, Paul; Bell, Martin; Bannister, Keith; Greiner, Jochen; Klose, Sylvio; Ghirlanda, Giancarlo

    2014-04-01

    Short γ-ray bursts (SGRBs) are the most elusive among GRBs with just a few of them having being studied pan- chromatically. Only three SGRBs have been detected in the radio band in the last 14 years. Radio observations of short GRBs should provide fundamental parameters of the physical process acting in these sources and on the nature of their progenitors. The detection of even a few more short GRBs in the radio band could constrain their true energetics, their radiative efficiency and the density of the environment where they happen (with immediate implications on the nature of their progenitors). The proposed joint radio-optical observations, will allow us for the first time to probe the hydrodynamics of the explosion and the radiation mechanism. We were graded 3.8 for two semesters, but the NAPA was not triggered.

  1. The quest for short GRB radio afterglows

    NASA Astrophysics Data System (ADS)

    Burlon, Davide; Gaensler, Bryan; Murphy, Tara; Hancock, Paul; Bell, Martin; Bannister, Keith; Greiner, Jochen; Klose, Sylvio; Ghirlanda, Giancarlo

    2014-10-01

    Short γ-ray bursts (SGRBs) are the most elusive among GRBs with just a few of them having being studied pan- chromatically. Only three SGRBs have been detected in the radio band in the last 14 years. Radio observations of short GRBs should provide fundamental parameters of the physical process acting in these sources and on the nature of their progenitors. The detection of even a few more short GRBs in the radio band could constrain their true energetics, their radiative efficiency and the density of the environment where they happen (with immediate implications on the nature of their progenitors). The proposed joint radio-optical observations, will allow us for the first time to probe the hydrodynamics of the explosion and the radiation mechanism. We were graded 3.8 for two semesters, but the NAPA was not triggered.

  2. Flowing Afterglow Vapor Deposition for Microelectric Applications.

    DTIC Science & Technology

    1987-04-28

    apparatus is intended to center on the deposition process itself. This includes the development of an in situ optical imaging technique that permits...This technique has the potential for circumventing the limitations of previous approaches. The FACVD process is a complicated mix of physical deposition...is being separately developed in a detailed and complicated construction process . The work has been supported for the past year by NSF and, in part

  3. Gamma ray bursts and their afterglows

    NASA Astrophysics Data System (ADS)

    Nicuesa Guelbenzu, A.

    2017-03-01

    Gamma-Ray Bursts (GRBs) were among the greatest mysteries in modern astrophysics. They were first observed 50 years ago but it took three decades before optical counterparts could be found and the underlying physical phenomena studied in detail. GRB research represents currently one of the most rapidly growing areas in extragalactic astronomy. This is due in large part to the numerous connections that GRBs have with other disciplines like cosmology, supernovae, stellar evolution, nuclear physics, astroparticle and gravitational wave astronomy. Therefore, their study is of great importance to understand various astrophysical phenomena such as the formation of the first stars, the chemical evolution and the expansion of the Universe. Since gamma radiation can travel along cosmological distances without being affected by any possible intervening absorption, GRBs can be detected from the most distant universe, reaching redshifts up to z = 10 or more.

  4. Xe2 gerade Rydberg states observed in the afterglow of a microplasma by laser spectroscopy of a^3 {Σ }_u^ + ( {1_u,O_u^ - }) absorption in the green (545-555 nm) and near-infrared (675-800 nm)

    NASA Astrophysics Data System (ADS)

    Wagner, C. J.; Galvin, T. C.; Eden, J. G.

    2014-06-01

    Bound←bound transitions of the Xe dimer at small internuclear separation (R < 4.0 Å) have been observed in the 545-555 nm and 675-800 nm spectral regions by laser spectroscopy in the afterglow of a pulsed Xe microplasma with a volume of ˜160 nl. Transient suppression of Xe2 A^1 {Σ }_u^ + ( {O_u^ + }) to X^1 {Σ }_g^ + ( {O_g^ + }) emission in the vacuum ultraviolet (˜172 nm), induced by laser excitation of {Ω }_g leftarrow a^3 {Σ }_u^ + ( {1_u,O_u^ - }) [Rydberg←Rydberg] transitions of the molecule, has confirmed the existence of structure between 720 and 770 nm (reported by Killeen and Eden [J. Chem. Phys. 84, 6048 (1986)]) but also reveals red-degraded vibrational bands extending to wavelengths beyond 800 nm. Spectral simulations based on calculations of Franck-Condon factors for assumed {Ω }_g leftarrow a^3 {Σ }_u^ + transitions involving Ω = 0±,1 gerade Rydberg states suggest that the upper level primarily responsible for the observed spectrum is an Ω = 1 state correlated, in the separated atom limit, with Xe(5p6 1S0) + Xe(5p5 6p) and built on a predominantly A2Π3/2g molecular ion core. Specifically, the spectroscopic constants for the upper state of the 1_g leftarrow 1_u,O_u^ ± absorptive transitions are determined to be Te = 13 000 ± 150 cm-1, ω _e^' = 120 ± 10 cm^{ - 1}, ω _e^' x_e^' = 1.1 ± 0.4 cm^{ - 1}, De = 3300 ± 300 cm-1, and {Δ }R_e = R_e^' - R_e^' ' } = 0.3 ± 0.1 {Å} which are in general agreement with the theoretical predictions of the pseudopotential hole-particle formalism, developed by Jonin and Spiegelmann [J. Chem. Phys. 117, 3059 (2002)], for both the (5)1g and ( 3)O_g^ + states of Xe2. These spectra exhibit the most extensive vibrational development, and provide evidence for the first molecular core-switching transition, observed to date for any of the rare gas dimers at small R (<4 Ǻ). Experiments in the green (545-555 nm) also provide improved absorption spectra, relative to data reported in 1986 and 1999

  5. The Quest for Short Gamma-ray Burst Radio Afterglows

    NASA Astrophysics Data System (ADS)

    Burlon, Davide; Gaensler, Bryan; Murphy, Tara; Hancock, Paul; Bell, Martin; Bannister, Keith; Greiner, Jochen; Klose, Sylvio; Ghirlanda, Giancarlo; Nardini, Marco

    2013-04-01

    Short Gamma-ray bursts (SGRBs) are the most elusive among GRBs with just a few of them having being studied pan- chromatically. Only two SGRBs have been detected in the radio band in the last 14 years. Radio observations of short GRBs should provide fundamental parameters of the physical process acting in these sources and on the nature of their progenitors. The detection of even a few more short GRBs in the radio band could constrain their true energetics, their radiative efficiency and the density of the environment where they happen (with immediate implications on the nature of their progenitors). The proposed joint radio-optical observations, will allow us for the first time to probe the hydrodynamics of the explosion and the radiation mechanism.

  6. The Quest for Short Gamma-ray Burst Radio Afterglows

    NASA Astrophysics Data System (ADS)

    Burlon, Davide; Murphy, Tara; Hancock, Paul; Bell, Martin; Bannister, Keith; Greiner, Jochen; Klose, Sylvio; Ghirlanda, Giancarlo; Nardini, Marco

    2012-10-01

    Short Gamma-ray bursts (SGRBs) are the most elusive among GRBs with just a few of them having being studied pan- chromatically. Only two SGRBs have been detected in the radio band in the last 14 years. Radio observations of short GRBs should provide fundamental parameters of the physical process acting in these sources and on the nature of their progenitors. The detection of even a few more short GRBs in the radio band could constrain their true energetics, their radiative efficiency and the density of the environment where they happen (with immediate implications on the nature of their progenitors). The proposed joint radio-optical observations, will allow us for the first time to probe the hydrodynamics of the explosion and the radiation mechanism.

  7. The γ-ray afterglows of tidal disruption events

    PubMed Central

    Chen, Xian; Gómez-Vargas, Germán Arturo; Guillochon, James

    2016-01-01

    A star wandering too close to a supermassive black hole (SMBH) will be tidally disrupted. Previous studies of such ‘tidal disruption event’ (TDE) mostly focus on the stellar debris that are bound to the system, because they give rise to luminous flares. On the other hand, half of the stellar debris in principle are unbound and can stream to a great distance, but so far there is no clear evidence that this ‘unbound debris stream’ (UDS) exists. Motivated by the fact that the circum-nuclear region around SMBHs is usually filled with dense molecular clouds (MCs), here we investigate the observational signatures resulting from the collision between an UDS and an MC, which is likely to happen hundreds of years after a TDE. We focus on γ-ray emission (0.1–105 GeV), which comes from the encounter of shock-accelerated cosmic rays with background protons and, more importantly, is not subject to extinction. We show that because of the high proton density inside an MC, the peak γ-ray luminosity, about 1039 erg s−1, is at least 100 times greater than that in the case without an MC (only with a smooth interstellar medium). The luminosity decays on a time-scale of decades, depending on the distance of the MC, and about a dozen of these ‘TDE afterglows’ could be detected within a distance of about 16 Mpc by the future Cherenkov Telescope Array. Without careful discrimination, these sources potentially could contaminate the searches for starburst galaxies, galactic nuclei containing millisecond pulsars or dark matter annihilation signals. PMID:27453685

  8. NASA Space Observatories Glimpse Faint Afterglow of Nearby Stellar Explosion

    NASA Astrophysics Data System (ADS)

    2005-10-01

    Intricate wisps of glowing gas float amid a myriad of stars in this image created by combining data from NASA's Hubble Space Telescope and Chandra X-ray Observatory. The gas is a supernova remnant, cataloged as N132D, ejected from the explosion of a massive star that occurred some 3,000 years ago. This titanic explosion took place in the Large Magellanic Cloud, a nearby neighbor galaxy of our own Milky Way. The complex structure of N132D is due to the expanding supersonic shock wave from the explosion impacting the interstellar gas of the LMC. Deep within the remnant, the Hubble visible light image reveals a crescent-shaped cloud of pink emission from hydrogen gas, and soft purple wisps that correspond to regions of glowing oxygen emission. A dense background of colorful stars in the LMC is also shown in the Hubble image. The large horseshoe-shaped gas cloud on the left-hand side of the remnant is glowing in X-rays, as imaged by Chandra. In order to emit X-rays, the gas must have been heated to a temperature of about 18 million degrees Fahrenheit (10 million degrees Celsius). A supernova-generated shock wave traveling at a velocity of more than four million miles per hour (2,000 kilometers per second) is continuing to propagate through the low-density medium today. The shock front where the material from the supernova collides with ambient interstellar material in the LMC is responsible for these high temperatures. Chandra image of N132D Chandra image of N132D, 2002 It is estimated that the star that exploded as a supernova to produce the N132D remnant was 10 to 15 times more massive than our own Sun. As fast-moving ejecta from the explosion slam into the cool, dense interstellar clouds in the LMC, complex shock fronts are created. A supernova remnant like N132D provides a rare opportunity for direct observation of stellar material, because it is made of gas that was recently hidden deep inside a star. Thus it provides information on stellar evolution and the creation of chemical elements such as oxygen through nuclear reactions in their cores. Such observations also help reveal how the interstellar medium (the gas that occupies the vast spaces between the stars) is enriched with chemical elements because of supernova explosions. Later on, these elements are incorporated into new generations of stars and their accompanying planets. Visible only from Earth's southern hemisphere, the LMC is an irregular galaxy lying about 160,000 light-years from the Milky Way. The supernova remnant appears to be about 3,000 years old, but since its light took 160,000 years to reach us, the explosion actually occurred some 163,000 years ago. This composite image of N132D was created by the Hubble Heritage team from visible-light data taken in January 2004 with Hubble's Advanced Camera for Surveys, and X-ray images obtained in July 2000 by Chandra's Advanced CCD Imaging Spectrometer. This marks the first Hubble Heritage image that combines pictures taken by two separate space observatories. The Hubble data include color filters that sample starlight in the blue, green, and red portions of the spectrum, as well as the pink emission from glowing hydrogen gas. The Chandra data are assigned blue in the color composite, in accordance with the much higher energy of the X-rays, emitted from extremely hot gas. This gas does not emit a significant amount of optical light, and was only detected by Chandra. Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) Acknowledgment: J.C. Green (Univ. of Colorado) and the Cosmic Origins Spectrograph (COS) GTO team; NASA/CXO/SAO Electronic image files, video, illustrations and additional information are available at: http://hubblesite.org/news/2005/30 http://heritage.stsci.edu/2005/30 The Space Telescope Science Institute (STScI) is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA).

  9. The Optical Afterglow of GRB 971214: R and J Photometry

    NASA Astrophysics Data System (ADS)

    Diercks, A. H.; Deutsch, E. W.; Castander, F. J.; Corson, C.; Gilmore, G.; Lamb, D. Q.; Tanvir, N.; Turner, E. L.; Wyse, R.

    1998-08-01

    We present an R- and J-band photometry of an optical transient that is likely to be associated with the gamma-ray burst event GRB 971214. Our first measurement took place 13 hr after the gamma-ray event. The brightness decayed with a power-law exponent α=-1.20+/-0.02, which is similar to those of GRB 970228 andGRB 970508, which had exponents of α=-1.10+/-0.04 and α=-1.141+/-0.014, respectively. The transient decayed monotonically during the first 4 days following the gamma-ray event in contrast with the optical transient associated with GRB 970508, which increased in brightness, peaking 2 days after the burst, before settling to a power-law decay.

  10. Spontaneous Raman scattering: a useful tool for investigating the afterglow of nanosecond scale discharges in air

    NASA Astrophysics Data System (ADS)

    Lo, A.; Cléon, G.; Vervisch, P.; Cessou, A.

    2012-04-01

    Nanosecond scale discharges are considered an interesting way for assisting combustion by enhancing either flame stabilization or ignition. Better understanding of energy deposit and radical species production processes is still required under pressure conditions normally encountered in combustion. The purpose of the present paper is to show that spontaneous Raman scattering, seldom used to investigate nanosecond pulsed discharges, is a useful measurement method for investigating the energy deposit of these discharges. The advantage of spontaneous Raman scattering is described by analyzing N2 and O2 spectra during the post-discharge of a filamentary nanosecond air discharge under atmospheric pressure, using phase-locked average spectra. The main advantages of spontaneous Raman scattering measurements are that they allow line-wise probing of different species with the same experimental setup and the determination of vibrational distribution by comparison with theoretical modeling over a wide range of vibrational levels (from v=0 to v=20 for N2). The model proposed takes into account the high level of vibrational excitation and the strong non-equilibrium observed, allowing the characterization of the vibrational relaxation over the complete post-discharge duration. Although the rotational structure is not resolved, the rotational temperature and thus translational temperature are determined with a moderate uncertainty for T above 500 K.

  11. A Leptonic-Hadronic Model for the Afterglow of Gamma-Ray Burst 090510

    DTIC Science & Technology

    2010-11-20

    e± pair dominated environment ( Ghirlanda et al. 2010; Ghisellini et al. 2010), an adiabatic fireball in a low-density medium and small magnetic field...Waxman, E. 2001, ApJ, 547, 922 Gao, W.-H., Mao, J., Xu, D., & Fan, Y.-Z. 2009, ApJ, 706, L33 Gehrels, N., et al. 2004, ApJ, 611, 1005 Ghirlanda ...G., Ghisellini, G., & Nava, L. 2010, A&A, 510, L7 Ghisellini, G., Ghirlanda , G., Nava, L., & Celotti, A. 2010, MNRAS, 403, 926 Granot, J., & Sari, R

  12. Infrared Chemiluminescence Studies of Ion-Molecule Reactions in a Flowing Afterglow.

    DTIC Science & Technology

    1982-01-01

    Polanyi , J. C., and Woodall, K. B. (1972). J. Chem. Phys. 57, 1547. McFarland, M., Albritton, D. L., Fehsenfeld, F. C., Ferguson, E. E., and Schmeltekopf...of Ion-Molecule Reaction Dynamics." Charles E. Hamilton: Graduate Research Associate, NSF Predoctoral Fellow. Michael A. Duncan: NRC Postdoctoral

  13. Happy Birthday Swift: Ultra-long GRB 141121A and Its Broadband Afterglow

    NASA Astrophysics Data System (ADS)

    Cucchiara, A.; Veres, P.; Corsi, A.; Cenko, S. B.; Perley, D. A.; Lien, A.; Marshall, F. E.; Pagani, C.; Toy, V. L.; Capone, J. I.; Frail, D. A.; Horesh, A.; Modjaz, M.; Butler, N. R.; Littlejohns, O. M.; Watson, A. M.; Kutyrev, A. S.; Lee, W. H.; Richer, M. G.; Klein, C. R.; Fox, O. D.; Prochaska, J. X.; Bloom, J. S.; Troja, E.; Ramirez-Ruiz, E.; de Diego, J. A.; Georgiev, L.; González, J.; Román-Zúñiga, C. G.; Gehrels, N.; Moseley, H.

    2015-10-01

    We present our extensive observational campaign on the Swift-discovered GRB 141121A, almost 10 years after its launch. Our observations cover radio through X-rays and extend for more than 30 days after discovery. The prompt phase of GRB 141121A lasted 1410 s and, at the derived redshift of z = 1.469, the isotropic energy is Eγ,iso = 8.0 × 1052 erg. Due to the long prompt duration, GRB 141121A falls into the recently discovered class of ultra-long GRBs (UL-GRBs). Peculiar features of this burst are (1) a flat early-time optical light curve and (2) a radio-to-X-ray rebrightening around three days after the burst. The latter is followed by a steep optical-to-X-ray decay and a much shallower radio fading. We analyze GRB 141121A in the context of the standard forward-reverse shock (FS, RS) scenario and we disentangle the FS and RS contributions. Finally, we comment on the puzzling early-time (t ≲ 3 days) behavior of GRB 141121A, and suggest that its interpretation may require a two-component jet model. Overall, our analysis confirms that the class of UL-GRBs represents our best opportunity to firmly establish the prominent emission mechanisms in action during powerful gamma-ray burst explosions, and future missions (like SVOM, XTiDE, or ISS-Lobster) will provide many more of such objects.

  14. HAPPY BIRTHDAY SWIFT: ULTRA-LONG GRB 141121A AND ITS BROADBAND AFTERGLOW

    SciTech Connect

    Cucchiara, A.; Veres, P.; Corsi, A.; Cenko, S. B.; Marshall, F. E.; Kutyrev, A. S.; Perley, D. A.; Horesh, A.; Lien, A.; Pagani, C.; Toy, V. L.; Capone, J. I.; Frail, D. A.; Modjaz, M.; Butler, N. R.; Littlejohns, O. M.; Watson, A. M.; Lee, W. H.; Richer, M. G.; Klein, C. R.; and others

    2015-10-20

    We present our extensive observational campaign on the Swift-discovered GRB 141121A, almost 10 years after its launch. Our observations cover radio through X-rays and extend for more than 30 days after discovery. The prompt phase of GRB 141121A lasted 1410 s and, at the derived redshift of z = 1.469, the isotropic energy is E{sub γ,iso} = 8.0 × 10{sup 52} erg. Due to the long prompt duration, GRB 141121A falls into the recently discovered class of ultra-long GRBs (UL-GRBs). Peculiar features of this burst are (1) a flat early-time optical light curve and (2) a radio-to-X-ray rebrightening around three days after the burst. The latter is followed by a steep optical-to-X-ray decay and a much shallower radio fading. We analyze GRB 141121A in the context of the standard forward–reverse shock (FS, RS) scenario and we disentangle the FS and RS contributions. Finally, we comment on the puzzling early-time (t ≲ 3 days) behavior of GRB 141121A, and suggest that its interpretation may require a two-component jet model. Overall, our analysis confirms that the class of UL-GRBs represents our best opportunity to firmly establish the prominent emission mechanisms in action during powerful gamma-ray burst explosions, and future missions (like SVOM, XTiDE, or ISS-Lobster) will provide many more of such objects.

  15. Cyclotron instability in the afterglow mode of minimum-B ECRIS

    SciTech Connect

    Izotov, I. Mansfeld, D.; Kalvas, T.; Koivisto, H.; Komppula, J.; Kronholm, R.; Laulainen, J.; Tarvainen, O.; Skalyga, V.

    2016-02-15

    It was shown recently that cyclotron instability in non-equilibrium plasma of a minimum-B electron cyclotron resonance ion source (ECRIS) causes perturbation of the extracted ion current and generation of strong bursts of bremsstrahlung emission, which limit the performance of the ion source. The present work is devoted to the dynamic regimes of plasma instability in ECRIS operated in pulsed mode. Instability develops in decaying plasma shortly after heating microwaves are switched off and manifests itself in the form of powerful pulses of electromagnetic emission associated with precipitation of high energy electrons. Time-resolved measurements of microwave emission bursts are presented. It was found that even in various gases (helium and oxygen were studied) and at different values of magnetic field and heating power, the dynamic spectra demonstrate common features: decreasing frequency within a single burst as well as from one burst to another.

  16. Cyclotron instability in the afterglow mode of minimum-B ECRIS

    NASA Astrophysics Data System (ADS)

    Izotov, I.; Kalvas, T.; Koivisto, H.; Komppula, J.; Kronholm, R.; Laulainen, J.; Mansfeld, D.; Skalyga, V.; Tarvainen, O.

    2016-02-01

    It was shown recently that cyclotron instability in non-equilibrium plasma of a minimum-B electron cyclotron resonance ion source (ECRIS) causes perturbation of the extracted ion current and generation of strong bursts of bremsstrahlung emission, which limit the performance of the ion source. The present work is devoted to the dynamic regimes of plasma instability in ECRIS operated in pulsed mode. Instability develops in decaying plasma shortly after heating microwaves are switched off and manifests itself in the form of powerful pulses of electromagnetic emission associated with precipitation of high energy electrons. Time-resolved measurements of microwave emission bursts are presented. It was found that even in various gases (helium and oxygen were studied) and at different values of magnetic field and heating power, the dynamic spectra demonstrate common features: decreasing frequency within a single burst as well as from one burst to another.

  17. Wide-field X-ray afterglow searches for gravitational wave events

    NASA Astrophysics Data System (ADS)

    Shawhan, Peter; Tervala, Justin

    2015-04-01

    The Advanced LIGO and Virgo gravitational wave (GW) detectors are on track to begin collecting science data soon and to reach full sensitivity by 2019. Low-latency analysis of the GW data will provide triggers for astronomers to seek electromagnetic transient counterparts. Many instruments will contribute to that effort, but instruments with very large fields of view will have a natural advantage for following up the typically large GW error regions. In particular, we consider ISS-Lobster, a proposed NASA mission to be deployed on the International Space Station, which features a focusing imager for soft X-rays with a field of view of over 800 square degrees. Our study using binary neutron star coalescence simulations from Singer et al. shows that a single ISS-Lobster pointing will, on average, cover over 95% of a LIGO-Virgo 3-detector sky map, while even a 2-detector sky map can be over 85% covered (on average) by a sequence of four pointings. We gratefully acknowledge the support of NSF Grants PHY-1068549 and PHY-1404121.

  18. Recombination Kinetics in the Afterglow of a High-Pressure Arc

    NASA Astrophysics Data System (ADS)

    Gleizes, Alain

    2000-10-01

    Modern high-voltage circuit-breakers are filled up with SF6 gas at a pressure of several atmospheres. AC current interruption occurs after current zero during a short phase of a few microseconds characterized by a fast cooling of the arc plasma due to convection and turbulence produced by overpressure effects. During this quenching phase the electrical conductance of the plasma and thus the electron number density must decrease rapidly in order to create a dielectric medium between the contacts capable to withstand the recovery voltage. We present first a kinetics study based on thermal equilibrium and on the previous knowledge of the temperature evolution, showing that the electrons disappear mainly by three mechanisms: three-body recombination at high temperature; dissociative recombination and dissociative attachment at intermediate and low temperature. A second study, coupling chemical kinetics and a two-dimension hydrodynamic modeling, has been performed in two conditions: thermal equilibrium and two-temperature plasma. The results show that departures from equilibrium remain weak, because in particular of the recombination of the electrons with S2+ ions. Finally, we will present the study of an SF6 and SF6-N2 arc plasma recombination in the presence of impurities. The theoretical prediction of the by-product formation has been compared with some experimental results obtained by gas chromatography, demonstrating the role of oxygen and carbon in the recombining plasma.

  19. Afterglow emission from xenon, krypton, and argon dimers in nanosecond volume discharge at elevated pressures

    NASA Astrophysics Data System (ADS)

    Baksht, E. Kh.; Lomaev, M. I.; Rybka, D. V.; Tarasenko, V. F.

    2006-10-01

    The emission characteristics of plasma of a volume discharge initiated by electron avalanche beams in heavy inert gases at pressures up to 1.5 bar have been studied. It is established that more than 90% of the energy radiated in the wavelength range from 120 to 850 nm is emitted from xenon, krypton, and argon dimers. In the case of excited xenon plasma, an output radiation power of ˜300 kW and an energy of 45 mJ per cubic centimeter were obtained.

  20. Electric Discharge and Afterglow Kinetics for Laser Mixtures with Carbon Monoxide, Oxygen and Iodine

    DTIC Science & Technology

    2006-01-01

    place in the active media of different electric discharge and chemical lasers. 15. SUBJECT TERMS EOARD, Physics, Optics 16 ...Mikheev 15. Dr. A.A. Shel 16 . Dr. S.Yu.Savinov 17. Yu.M. Klimach 18. N.A. Ionina 19. S.A. Vetoshkin 20. A.Yu. Kozlov 21. O.A.Rulev 22. Yu.V...mixtures, laser cavity and excitation pulse, selected in the kinetic modelling. Gas density (Amagat) 0.2 Gas temperature (K) 100 E/N (10- 16 V cm2) 1

  1. Panchromatic Observations of the Textbook GRB 110205A: Constraining Physical Mechanisms of Prompt Emission and Afterglow

    NASA Technical Reports Server (NTRS)

    Zheng, W.; Shen, R. F.; Sakamoto, T.; Beardmore, A. P.; De Pasquale, M.; Wu, X. F.; Gorosabel, J.; Urata, Y.; Sugita, S.; Zhang, B.; Pozanenko, A.; Nissinen, M.; Sahu, D. K.; Im, M.; Ukwatta, T. N.; Andreev, M.; Klunko, E.; Volnova, A.; Akerlof, C. W.; Anto, P.; Barthelmy, S. D.; Breeveld, A.; Carsenty, U.; Gehrels, N.; Sonbas, E.

    2011-01-01

    We present a comprehensive analysis of a bright, long duration (T(sub 90) approx. 257 s) GRB 110205A at redshift z = 2.22. The optical prompt emission was detected by Swift/UVOT, ROTSE-IIIb and BOOTES telescopes when the GRB was still radiating in the gamma-ray band. Thanks to its long duration, nearly 200 s of observations were obtained simultaneously from optical, X-ray to gamma-ray (1 eV - 5 MeV), which makes it one of the exceptional cases to study the broadband spectral energy distribution across 6 orders of magnitude in energy during the prompt emission phase. In particular, by fitting the time resolved prompt spectra, we clearly identify, for the first time, an interesting two-break energy spectrum, roughly consistent with the standard GRB synchrotron emission model in the fast cooling regime. Although the prompt optical emission is brighter than the extrapolation of the best fit X/ -ray spectra, it traces the -ray light curve shape, suggesting a relation to the prompt high energy emission. The synchrotron + synchrotron self-Compton (SSC) scenario is disfavored by the data, but the models invoking a pair of internal shocks or having two emission regions can interpret the data well. Shortly after prompt emission (approx. 1100 s), a bright (R = 14.0) optical emission hump with very steep rise ( alpha approx. 5.5) was observed which we interpret as the emission from the reverse shock. It is the first time that the rising phase of a reverse shock component has been closely observed.

  2. Study of the process of dust grain discharging in the afterglow of an RF discharge

    SciTech Connect

    Filatova, I. I.; Trukhachev, F. M.; Chubrik, N. I.

    2011-12-15

    The process of decay of dust structures formed of polydisperse grains injected into an RF discharge is investigated. The dust grain velocities after switching-off of the discharge are measured. The number density, dimensions, and residual charges of dust grains are estimated from the balance of forces acting on the grains after discharge is switched off.

  3. Relativistic Particle-In-Cell Simulation Studies of Prompt and Early Afterglows from GRBs

    NASA Technical Reports Server (NTRS)

    Nishikawa, Ken-Ichi; Hardee, Philip; Mizuno, Yosuke; Fishman, Gerald

    2008-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electro-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the collisionless relativistic shock particle acceleration is due to plasma waves and their associated instabilities {e.g., the Weibel (filamentation) instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.-/

  4. New Relativistic Particle-In-Cell Simulation Studies of Prompt and Early Afterglows from GRBs

    NASA Technical Reports Server (NTRS)

    Nishikawa, Ken-ichi; Hardee, P.; Mizuno, Y.; Zhang, B.; Medvedev, M.; Hartmann, D.; Fishman, J. F.; Preece, R.

    2008-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electro-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the collisionless relativistic shock particle acceleration is due to plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  5. Relativistic Particle-in-Cell Simulation Studies of Prompt and Early Afterglows Observed by GLAST

    NASA Technical Reports Server (NTRS)

    Mizuno, Y.; Nishikawa, K.-I.; Hardee, P.; Fishman, G. J.; Preece, R.

    2007-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "'jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  6. Radio Afterglow of the Jetted Tidal Disruption Event Swift J1644+57

    NASA Astrophysics Data System (ADS)

    Metzger, B. D.; Giannios, D.; Mimica, P.

    2013-07-01

    The recent transient event Swift J1644+57 has been interpreted as resulting from a relativistic outflow, powered by the accretion of a tidally disrupted star onto a supermassive black hole. This discovery of a new class of relativistic transients opens new windows into the study of tidal disruption events (TDEs) and offers a unique probe of the physics of relativistic jet formation and the conditions in the centers of distant quiescent galaxies. Unlike the rapidly-varying γ/X-ray emission from Swift J1644+57, the radio emission varies more slowly and is well modeled as synchrotron radiation from the shock interaction between the jet and the gaseous circumnuclear medium (CNM). Early after the onset of the jet, a reverse shock propagates through and decelerates the ejecta released during the first few days of activity, while at much later times the outflow approaches the self-similar evolution of Blandford and McKee. The point at which the reverse shock entirely crosses the earliest ejecta is clearly observed as an achromatic break in the radio light curve at t ≈ 10 days. I discuss the implications of Swift J1644+57 for the fraction of TDEs accompanied by relativistic jets; the physics of jet formation more broadly; and the prospects for detecting off-axis TDE radio emission, either via follow-up observations of TDE candidates discovered at other wavelengths or blindly with upcoming wide-field radio surveys.

  7. BEAM ON TARGET MODEL Produces All Gamma Ray Burst Phenomena Including Afterglow

    NASA Astrophysics Data System (ADS)

    Greyber, H.

    2000-12-01

    While one must applaud the splendid research by L. Piro et al and L. Amati et al reported in SCIENCE recently, one must question, as M. Rees and S. Woolsey have done, their conclusion that a ``supranova model" is the only explanation for these new X-ray observations. In fact L. Piro was quoted as saying, ``Our data helps rule out the scenario where two neutron stars or black holes collide. We think GRBs result from something similar to a supernova explosion, but much more powerful." A relatively unknown physical model for GRBs, Greyber's Beam On Target model (BOT), dating back to the first CGRO observations, can plausibly explain the iron emission lines observed for GRB991216, and also the mass of the dense medium within a light-day of the GRB being roughly equivalent to at least one-tenth solar mass, as well as the initial shedding of material followed by the GRB event. When a galaxy forms under gravitational collapse in the presence of a primordial magnetic field, Mestel and Strittmatter demonstrated that, for finite Ohmic diffusion, a growing equatorial current loop is formed. Even if this stable ``Storage Ring" has only 10exp-9 of the total energy released during a typical galaxy's formation, the relativistic beam can possess 10exp58 ergs. The GRB ``fireball" occurs when a target star races across the powerful beam, blowing off target material as a hot, rapidly expanding plasma cloud, simulating an explosion. Since currents in space are known to be sometimes filamentary, sharp millisecond spikes can be expected in some GRBs. Proton and alpha particle nuclear reactions produce a gamma ray beam. Beam particles impinging on denser cloud material create an electromagnetic shower, producing X-ray, optical and radio radiation. Since the Storage Ring has an intense magnetic field around it, synchrotron radiation is expected. The beam, striking a highly evolved massive target star, produces the iron emission lines. H. D. Greyber, in ``After the Dark Ages:When Galaxies Were Young", A.I.P. Confer. Proc. no.470, 388, (1999) L. Mestel & P. Strittmatter, Mon. Not. Royal Astron. Society, 137, 95, (1967)

  8. Beam On Target (BOT) Produces Gamma Ray Burst (GRB) Fireballs and Afterglows

    NASA Astrophysics Data System (ADS)

    Greyber, H. D.

    1997-12-01

    Unlike the myriads of ad hoc models that have been offered to explain GRB, the BOT process is simply the very common process used worldwide in accelerator laboratories to produce gamma rays. The Strong Magnetic Field (SMF) model postulates an extremely intense, highly relativistic current ring formed during the original gravitational collapse of a distant galaxy when the plasma cloud was permeated by a primordial magnetic field. GRB occur when solid matter (asteroid, white dwarf, neutron star, planet) falls rapidly through the Storage Ring beam producing a very strongly collimated electromagnetic shower, and a huge amount of matter from the target, in the form of a giant, hot, expanding plasma cloud, or ``Fireball,'' is blown off. BOT satisfies all the ``severe constraints imposed on the source of this burst --'' concluded by the CGRO team (Sommer et al, Astrophys. J. 422 L63 (1994)) for the huge intense burst GRB930131, whereas neutron star merger models are ``difficult to reconcile.'' BOT expects the lowest energy gamma photons to arrive very slightly later than higher energy photons due to the time for the shower to penetrate the target. The millisecond spikes in bursts are due to the slender filaments of current that make up the Storage Ring beam. Delayed photons can be explained by a broken target ``rock.'' See H. Greyber in the book ``Compton Gamma Ray Observatory,'' AIP Conf. Proc. 280, 569 (1993).

  9. Vibrational and Rotational CARS Measurements of Nitrogen in Afterglow of Streamer Discharge in Atmospheric Pressure Fuel/Air Mixtures

    DTIC Science & Technology

    2012-01-01

    distribution unlimited 13. SUPPLEMENTARY NOTES J. Phys. D: Appl. Phys. 45 (2012) 495401 (8pp) 14. ABSTRACT The use of nonequilibrium plasma generated by...nanosecond discharges to ignite fuel/air mixtures, known as transient plasma ignition (TPI), has been shown to effectively reduce ignition delay and...improve engine performance relative to spark ignition for combustion engines. While this method is potentially useful for many engine applications, at

  10. Measurement and Visualization of Mass Transport for the Flowing Atmospheric Pressure Afterglow (FAPA) Ambient Mass-Spectrometry Source

    NASA Astrophysics Data System (ADS)

    Pfeuffer, Kevin P.; Ray, Steven J.; Hieftje, Gary M.

    2014-05-01

    Ambient desorption/ionization mass spectrometry (ADI-MS) has developed into an important analytical field over the last 9 years. The ability to analyze samples under ambient conditions while retaining the sensitivity and specificity of mass spectrometry has led to numerous applications and a corresponding jump in the popularity of this field. Despite the great potential of ADI-MS, problems remain in the areas of ion identification and quantification. Difficulties with ion identification can be solved through modified instrumentation, including accurate-mass or MS/MS capabilities for analyte identification. More difficult problems include quantification because of the ambient nature of the sampling process. To characterize and improve sample volatilization, ionization, and introduction into the mass spectrometer interface, a method of visualizing mass transport into the mass spectrometer is needed. Schlieren imaging is a well-established technique that renders small changes in refractive index visible. Here, schlieren imaging was used to visualize helium flow from a plasma-based ADI-MS source into a mass spectrometer while ion signals were recorded. Optimal sample positions for melting-point capillary and transmission-mode (stainless steel mesh) introduction were found to be near (within 1 mm of) the mass spectrometer inlet. Additionally, the orientation of the sampled surface plays a significant role. More efficient mass transport resulted for analyte deposits directly facing the MS inlet. Different surfaces (glass slide and rough surface) were also examined; for both it was found that the optimal position is immediately beneath the MS inlet.

  11. Flowing afterglow measurements of the density dependence of gas-phase ion-ion mutual neutralization reactions

    SciTech Connect

    Shuman, Nicholas S.; Viggiano, Albert A.; Johnsen, Rainer

    2013-05-28

    We have studied the dependence of several ion-ion mutual neutralization (MN) reactions on helium density in the range from 1.6 Multiplication-Sign 10{sup 16} to 1.5 Multiplication-Sign 10{sup 17} cm{sup -3} at 300 K, using the Variable Electron and Neutral Density Attachment Mass Spectrometry method. The rate coefficients of the reactions Ar{sup +}+ Br{sub 2}{sup -}, Ar{sup +}+ SF{sub 6}{sup -}, and Ar{sup +}+ C{sub 7}F{sub 14}{sup -} were found to be independent of gas density over the range studied, in disagreement with earlier observations that similar MN reactions are strongly enhanced at the same gas densities. The cause of the previous enhancement with density is traced to the use of 'orbital-motion-limit' theory to infer ion densities from the currents collected by ion-attracting Langmuir probes in a region where it is not applicable.

  12. A Rapid-Response Gamma-Ray Burst Afterglow Observing Program at Etelman Observatory in the US Virgin Islands

    NASA Astrophysics Data System (ADS)

    Giblin, Timothy W.; Neff, James E.; Hakkila, Jon; Hartmann, Dieter; Andresian-Thomas, Noretta; Drost, Donald M.

    2004-09-01

    The College of Charleston (CofC) is one of three institutions that belong to a consortium led by the Division of Science and Mathematics at the University of the Virgin Islands (UVI) to maintain and operate a research grade telescope at Etelman Observatory on the island of St. Thomas (18deg, 21' N, 65deg W at an elevation ~ 1325 ft with <= 1'' seeing). The location provides 80% sky coverage of the southern celestial hemisphere and, on average, ~ 6 hours of clear sky per night, except during the peak of hurricane season. This makes the observatory an ideal facility for observing Gamma-Ray Bursts (GRBs). The observatory will serve a variety of needs to the consortium members that include research, teaching, and public outreach. The primary research function of this facility will be to perform rapid, automated followup observations of Gamma-Ray Bursts (GRBs) observed with NASA's Swift spacecraft, to be launched in June 2004, via the GCN. The newly renovated observatory houses a new robotic 0.5 m Cassegrain telescope with a back-illuminated Marconi 2024 × 2024 CCD42-40 imaging array and 12-position UBVRI filter wheel. Assuming 1.5'' seeing and a S/N=5, we can obtain a limiting (unfiltered) magnitude of ~ 19 with a 10 s integration time. The slew rate is >= 10deg per second. With the exceptional sky coverage at Etelman Observatory, we anticipate a detection rate of about 10-15% of the Swift detection rate, and we anticipate making a significant contribution to the global network of small telescopes dedicated to GRB observations.

  13. Dynamic regimes of cyclotron instability in the afterglow mode of minimum-B electron cyclotron resonance ion source plasma

    NASA Astrophysics Data System (ADS)

    Mansfeld, D.; Izotov, I.; Skalyga, V.; Tarvainen, O.; Kalvas, T.; Koivisto, H.; Komppula, J.; Kronholm, R.; Laulainen, J.

    2016-04-01

    The paper is concerned with the dynamic regimes of cyclotron instabilities in non-equilibrium plasma of a minimum-B electron cyclotron resonance ion source operated in pulsed mode. The instability appears in decaying ion source plasma shortly (1-10 ms) after switching off the microwave radiation of the klystron, and manifests itself in the form of powerful pulses of electromagnetic emission associated with precipitation of high-energy electrons along the magnetic field lines. Recently it was shown that this plasma instability causes perturbations of the extracted ion current, which limits the performance of the ion source and generates strong bursts of bremsstrahlung emission. In this article we present time-resolved diagnostics of electromagnetic emission bursts related to cyclotron instability in the decaying plasma. The temporal resolution is sufficient to study the fine structure of the dynamic spectra of the electromagnetic emission at different operating regimes of the ion source. It was found that at different values of magnetic field and heating power the dynamic spectra demonstrate common features: Decreasing frequency from burst to burst and an always falling tone during a single burst of instability. The analysis has shown that the instability is driven by the resonant interaction of hot electrons, distributed between the electron cyclotron resonance (ECR) zone and the trap center, with slow extraordinary wave propagation quasi-parallel with respect to the external magnetic field.

  14. Flowing afterglow measurements of the density dependence of gas-phase ion-ion mutual neutralization reactions

    NASA Astrophysics Data System (ADS)

    Shuman, Nicholas S.; Viggiano, Albert A.; Johnsen, Rainer

    2013-05-01

    We have studied the dependence of several ion-ion mutual neutralization (MN) reactions on helium density in the range from 1.6 × 1016 to 1.5 × 1017 cm-3 at 300 K, using the Variable Electron and Neutral Density Attachment Mass Spectrometry method. The rate coefficients of the reactions Ar+ + Br2-, Ar+ + SF6-, and Ar+ + C7F14- were found to be independent of gas density over the range studied, in disagreement with earlier observations that similar MN reactions are strongly enhanced at the same gas densities. The cause of the previous enhancement with density is traced to the use of "orbital-motion-limit" theory to infer ion densities from the currents collected by ion-attracting Langmuir probes in a region where it is not applicable.

  15. An experimental study of plasma density determination by cylindrical Langmuir probe in a flowing afterglow plasma at elevated pressures

    SciTech Connect

    Kudrna, P.; Chudacek, O.; Sicha, M.; Tichy, M.

    1995-12-31

    The collection of positive ions by a cylindrical Langmuir probe at the pressures when the ion mean free path is much shorter than the probe sheath thickness (usually called the collisional case of positive ion collection) has been treated by several authors. The idea, that the ions can only be scattered by collisions with neutral particles and hence the effect of collisions results in the reduction of the ion current to the probe had to be corrected owing to the experimental facts which showed that the ion current in the presence of collisions can be greater than in the collisionless; case and hence results in greater apparent ion density compared to the electron one. A simple explanation of the fact that the ion current can be increased by the effect of collisions of positive ions with neutrals, has been brought up by Zakrzewski and Kopiczynski in and was based on the fact that the collisions can destroy the ion orbital motion in the space charge sheath surrounding the Langmuir probe and the ions have hence greater chance to be collected by the probe. The upper limit for the ion current increase has been set in to be the current calculated by the radial motion theory by Allen, the collisionless, current limit has been taken after Laframboise. Quantitatively this effect is described by a factor {gamma}{sub 1} which ranges from 1 in the collisionless case to the ratio I{sub A}/I{sub L}, where I{sub A} and I{sub L} are the ion collisionless. Simultaneously it is supposed in the work that the collisions can scatter ions which leads to the decrease of the ion current, the effect is described quantitatively by a factor {gamma}{sub 2}.

  16. Fast synthesis of ultrathin ZnO nanowires by oxidation of Cu/Zn stacks in low-pressure afterglow

    NASA Astrophysics Data System (ADS)

    Altaweel, A.; Imam, A.; Ghanbaja, J.; Mangin, D.; Miska, P.; Gries, T.; Belmonte, T.

    2017-02-01

    The synthesis of ultrathin, single-crystalline zinc oxide nanowires was achieved by treating in a flowing microwave plasma oxidation process, zinc films coated beforehand by a sputtered thin buffer layer of copper. The aspect ratio of the nanowires can be controlled by the following experimental parameters: treatment duration, furnace temperature, oxygen concentration. An average diameter of 6 nm correlated with a mean length of 750 nm can be reached with a fairly high surface number density for very short treatments, typically less than 1 min. The oxidized samples are characterized by means of SEM, XRD, SIMS, HRTEM and EDX techniques. Structural characterization reveals that these nanowires are single-crystalline, with the wurtzite phase of ZnO. Nanowires are only composed of ZnO without copper particles inside or at the end of the nanowires. Temperature-dependent photoluminescence measurements confirm that ZnO nanowires are of high crystalline quality and thin enough to produce quantum confinement.

  17. Fast synthesis of ultrathin ZnO nanowires by oxidation of Cu/Zn stacks in low-pressure afterglow.

    PubMed

    Altaweel, A; Imam, A; Ghanbaja, J; Mangin, D; Miska, P; Gries, T; Belmonte, T

    2017-02-24

    The synthesis of ultrathin, single-crystalline zinc oxide nanowires was achieved by treating in a flowing microwave plasma oxidation process, zinc films coated beforehand by a sputtered thin buffer layer of copper. The aspect ratio of the nanowires can be controlled by the following experimental parameters: treatment duration, furnace temperature, oxygen concentration. An average diameter of 6 nm correlated with a mean length of 750 nm can be reached with a fairly high surface number density for very short treatments, typically less than 1 min. The oxidized samples are characterized by means of SEM, XRD, SIMS, HRTEM and EDX techniques. Structural characterization reveals that these nanowires are single-crystalline, with the wurtzite phase of ZnO. Nanowires are only composed of ZnO without copper particles inside or at the end of the nanowires. Temperature-dependent photoluminescence measurements confirm that ZnO nanowires are of high crystalline quality and thin enough to produce quantum confinement.

  18. Measurement and visualization of mass transport for the flowing atmospheric pressure afterglow (FAPA) ambient mass-spectrometry source.

    PubMed

    Pfeuffer, Kevin P; Ray, Steven J; Hieftje, Gary M

    2014-05-01

    Ambient desorption/ionization mass spectrometry (ADI-MS) has developed into an important analytical field over the last 9 years. The ability to analyze samples under ambient conditions while retaining the sensitivity and specificity of mass spectrometry has led to numerous applications and a corresponding jump in the popularity of this field. Despite the great potential of ADI-MS, problems remain in the areas of ion identification and quantification. Difficulties with ion identification can be solved through modified instrumentation, including accurate-mass or MS/MS capabilities for analyte identification. More difficult problems include quantification because of the ambient nature of the sampling process. To characterize and improve sample volatilization, ionization, and introduction into the mass spectrometer interface, a method of visualizing mass transport into the mass spectrometer is needed. Schlieren imaging is a well-established technique that renders small changes in refractive index visible. Here, schlieren imaging was used to visualize helium flow from a plasma-based ADI-MS source into a mass spectrometer while ion signals were recorded. Optimal sample positions for melting-point capillary and transmission-mode (stainless steel mesh) introduction were found to be near (within 1 mm of) the mass spectrometer inlet. Additionally, the orientation of the sampled surface plays a significant role. More efficient mass transport resulted for analyte deposits directly facing the MS inlet. Different surfaces (glass slide and rough surface) were also examined; for both it was found that the optimal position is immediately beneath the MS inlet.

  19. Comparison of TALIF and catalytic probes for the determination of nitrogen atom density in a nitrogen plasma afterglow

    NASA Astrophysics Data System (ADS)

    Gaboriau, F.; Cvelbar, U.; Mozetic, M.; Erradi, A.; Rouffet, B.

    2009-03-01

    The density of neutral nitrogen atoms in a glass reactor was measured by two absolute methods: two-photon absorption laser induced fluorescence (TALIF) and catalytic probes. The source of N atoms was nitrogen plasma created in a quartz tube by surfatron microwave generator operating at 2.45 GHz and adjustable output power up to 300 W. The TALIF measurements were performed using a dye laser which was pumped by a YAG laser. At the exit of the dye laser, the beam frequency was doubled through a KDP crystal and then mixed in a BBO crystal. The wavelength of the output laser beam was chosen at 206.65 nm so two-photon absorption was suitable to excite nitrogen atoms from the ground state to the 5d 2D state. Absolute N density was determined by using calibration with krypton. Simultaneously, the N atom density was measured with a fiber optics catalytic probe (FOCP) with a well-activated iron catalytic tip. Measurements were performed by both methods at nitrogen flows between 0.2 and 2 l min-1, and discharge powers between 60 and 300 W. At rather high nitrogen flows, the N atom density increased monotonically with increasing discharge power, while at lower flow saturation was observed. TALIF showed somewhat higher values than FOCP which was attributed to the accuracy of both methods. The main advantage of TALIF is a broader detection range, while FOCP is an extremely simple and inexpensive technique.

  20. Afterglow model for the radio emission from the jetted tidal disruption candidate Swift J1644+57

    NASA Astrophysics Data System (ADS)

    Metzger, Brian D.; Giannios, Dimitrios; Mimica, Petar

    2012-03-01

    The recent transient event Swift J1644+57 has been interpreted as emission from a collimated relativistic jet, powered by the sudden onset of accretion on to a supermassive black hole following the tidal disruption of a star. Here we model the radio-microwave emission as synchrotron radiation produced by the shock interaction between the jet and the gaseous circumnuclear medium (CNM). At early times after the onset of the jet (t≲ 5-10 d) a reverse shock propagates through and decelerates the ejecta, while at later times the outflow approaches the Blandford-McKee self-similar evolution (possibly modified by additional late energy injection). The achromatic break in the radio light curve of Swift J1644+57 is naturally explained as the transition between these phases. We show that the temporal indices of the pre- and post-break light curve are consistent with those predicted if the CNM has a wind-type radial density profile n∝r-2. The observed synchrotron frequencies and self-absorbed flux constrain the fraction of the post-shock thermal energy in relativistic electrons ɛe≈ 0.03-0.1, the CNM density at 1018 cm n18≈ 1-10 cm-3 and the initial Lorentz factor Γj≈ 10-20 and opening angle ? of the jet. Radio modelling thus provides robust independent evidence for a narrowly collimated outflow. Extending our model to the future evolution of Swift J1644+57, we predict that the radio flux at low frequencies (ν≲ few GHz) will begin to brighten more rapidly once the characteristic frequency νm crosses below the radio band after it decreases below the self-absorption frequency on a time-scale of months (indeed, such a transition may already have begun). Our results demonstrate that relativistic outflows from tidal disruption events provide a unique probe of the conditions in distant, previously inactive galactic nuclei, complementing studies of normal active galactic nuclei.

  1. OT2_jforbric_3: Probing short-term far-infrared variability of protostars and exploring afterglows of X-ray disk heating

    NASA Astrophysics Data System (ADS)

    Forbrich, J.

    2011-09-01

    Recent studies have shown that there is a surprising amount of variability on many timescales in the mid-infrared emission of young stellar objects (YSOs). Especially on short timescales of minutes to hours, mid- and particularly far-infrared variability is currently almost entirely unexplored. While such variability is probing circumstellar disks and envelopes, it is linked to physical processes on the central object. Already the earliest evolutionary stages of YSOs are also strong X-ray emitters, and one important aspect is the heating and possible eventual dispersal of circumstellar disks due to X-ray emission. Even though very important for the understanding of planet formation, this process is poorly understood. The Herschel Space Observatory offers the last possibility for the foreseeable future to explore these processes in more detail and learn about disk heating and explore the occurrence of short-term variability. Here, we propose to do both by repeated observations of the extensively studied nearby Coronet cluster in the CrA star-forming region. Five epochs of near-simultaneous XMM-Newton and Herschel observations, each about 1.5h in duration and spaced by timescales of days to weeks, are meant to explore the short-term variability and link it to the more frequently studied variability on longer timescales. During each epoch, the cluster is mapped 18 times with Herschel. The Coronet has been chosen for having YSOs that can be detected at high S/N in short periods of time while not being too crowded for the angular resolution of both observatories. By exploring far-infrared variability on timescales of several minutes to days and weeks as well as disk heating by protostellar X-ray emission, these short observations will have a unique legacy value.

  2. Energies of GRB blast waves and prompt efficiencies as implied by modelling of X-ray and GeV afterglows

    NASA Astrophysics Data System (ADS)

    Beniamini, Paz; Nava, Lara; Duran, Rodolfo Barniol; Piran, Tsvi

    2015-11-01

    We consider a sample of 10 gamma-ray bursts with long-lasting ( ≳ 102 s) emission detected by Fermi/Large Area Telescope and for which X-ray data around 1 d are also available. We assume that both the X-rays and the GeV emission are produced by electrons accelerated at the external forward shock, and show that the X-ray and the GeV fluxes lead to very different estimates of the initial kinetic energy of the blast wave. The energy estimated from GeV is on average ˜50 times larger than the one estimated from X-rays. We model the data (accounting also for optical detections around 1 d, if available) to unveil the reason for this discrepancy and find that good modelling within the forward shock model is always possible and leads to two possibilities: (i) either the X-ray emitting electrons (unlike the GeV emitting electrons) are in the slow-cooling regime or (ii) the X-ray synchrotron flux is strongly suppressed by Compton cooling, whereas, due to the Klein-Nishina suppression, this effect is much smaller at GeV energies. In both cases the X-ray flux is no longer a robust proxy for the blast wave kinetic energy. On average, both cases require weak magnetic fields (10-6 ≲ ɛB ≲ 10-3) and relatively large isotropic kinetic blast wave energies 10^{53} erg<{E}_{0,kin}<10^{55} erg corresponding to large lower limits on the collimated energies, in the range 10^{52} erg<{E}_{θ ,kin}<5× 10^{52} erg for an ISM (interstellar medium) environment with n ˜ 1 cm-3 and 10^{52} erg<{E}_{θ ,kin}<10^{53} erg for a wind environment with A* ˜ 1. These energies are larger than those estimated from the X-ray flux alone, and imply smaller inferred values of the prompt efficiency mechanism, reducing the efficiency requirements on the still uncertain mechanism responsible for prompt emission.

  3. The Prompt-afterglow Connection in Gamma-ray Bursts: a Comprehensive Statistical Analysis of Swift X-ray Light-curves

    NASA Technical Reports Server (NTRS)

    Margutti, R.; Zaninoni, E.; Bernardini, M. G.; Chincarini, G.; Pasotti, F.; Guidorzi, C.; Angelini, Lorella; Burrows, D. N.; Capalbi, M.; Evans, P. A.; Gehrels, Neil; Kennea, J.; Mangano, V.; Moretti, A.; Nousek, J.; Osborne, J. P.; Page, K. L.; Perri, M.; Racusin, Judith Lea; Romano, P.; Sbarufatti, B.; Stafford, M.; Stamatikos, Michael

    2012-01-01

    We present a comprehensive statistical analysis of Swift X-ray light-curves of Gamma- Ray Bursts (GRBs) collecting data from more than 650 GRBs discovered by Swift and other facilities. The unprecedented sample size allows us to constrain the rest-frame X-ray properties of GRBs from a statistical perspective, with particular reference to intrinsic time scales and the energetics of the different light-curve phases in a common rest-frame 0.3-30 keV energy band. Temporal variability episodes are also studied and their properties constrained. Two fundamental questions drive this effort: i) Does the X-ray emission retain any kind of "memory" of the prompt ?-ray phase? ii) Where is the dividing line between long and short GRB X-ray properties? We show that short GRBs decay faster, are less luminous and less energetic than long GRBs in the X-rays, but are interestingly characterized by similar intrinsic absorption. We furthermore reveal the existence of a number of statistically significant relations that link the X-ray to prompt ?-ray parameters in long GRBs; short GRBs are outliers of the majority of these 2-parameter relations. However and more importantly, we report on the existence of a universal 3-parameter scaling that links the X-ray and the ?-ray energy to the prompt spectral peak energy of both long and short GRBs: E(sub X,iso)? E(sup 1.00+/-0.06)(sub ?,iso) /E(sup 0.60+/-0.10)(sub pk).

  4. Electron Affinity of trans-2-C4F8 from Electron Attachment-Detachment Kinetics

    DTIC Science & Technology

    2009-09-04

    over the temperature range employed in the present study. B. Kinetics Experiments. A flowing - afterglow Langmuir - probe (FALP) apparatus was used for... afterglow Langmuir - probe apparatus. Only parent anions were formed in the attachment process throughout this temperature range. At the highest... afterglow Langmuir - probe apparatus. Only parent anions were formed in the attachment process throughout this temperature range. At the highest

  5. Study of excitation transfer in a flowing helium afterglow pumped with a tuneable dye laser. II - Measurement of the rate coefficient for the rotational relaxation of He2/3p 3Pi-g/.

    NASA Technical Reports Server (NTRS)

    Collins, C. B.; Johnson, B. W.

    1972-01-01

    The results of the use of a fast-transient fluorescence technique in the examination of rotational relaxation caused by collisions with neutral helium atoms are discussed. Details regarding the production and detection of reacting species are considered, together with the analytical method used. A dye laser system with 4-methylcoumarin producing a pumping flux in the 4650 A region was employed in the investigations.

  6. Low-temperature VUV photoluminescence and thermoluminescence of UV excited afterglow phosphor Sr3AlxSi1-xO5:Ce(3+),Ln(3+) (Ln = Er, Nd, Sm, Dy and Tm).

    PubMed

    Luo, Hongde; Bos, Adrie J J; Dobrowolska, Anna; Dorenbos, Pieter

    2015-06-21

    Low-temperature (10 K) photoluminescence excitation and emission spectra of undoped Sr3SiO5 as well as Ce(3+) and Eu(3+) single doped Sr3SiO5 have been investigated. They show the host exciton band and the O(2-) to Eu(3+) charge transfer band at 5.98 eV (207 nm) and 3.87 eV (320 nm) respectively. Low-temperature thermoluminescence measurements are reported for Ce(3+) and lanthanide (Er, Nd, Sm, Dy, Er and Tm) co-doped Sr3AlxSi1-xO5. The results show that Ce(3+) is the recombination centre and Nd, Sm, Dy and Tm work as electron traps with trap depths of 0.95 eV, 1.89 eV, 1.02 eV, and 1.19 eV, respectively. Thermoluminescence excitation spectra of Sr2.98Al0.02Si0.98O5:0.01Ce(3+),0.01Dy(3+) show that the traps can be charged by 260 nm UV excitation.

  7. Electron Attachment to Cl2 from 300 to 1100 K: Experiment and Theory

    DTIC Science & Technology

    2009-03-01

    a high-temperature flowing - afterglow Langmuir - probe apparatus. /?-matrix calculations of the rate constants have been extended to 1100 K. Experi... afterglow Langmuir - probe apparatus, /{-matrix calculations have been carried out which compare well with the present measurements with possible...ABSTRACT Rate constants for dissociative electron attachment to Cl2 have been measured from 300 to 1100 K in a high-temperature flowing - afterglow

  8. Ion and Electron Interactions at Thermal and Suprathermal Energies

    DTIC Science & Technology

    1988-09-30

    The flowing afterglow / Langmuir probe (FALP) and the selected ion flow drift tube (SIFDT) apparatuses have been used to study (i) dissociative... flowing afterglow / Langmuir probe (VT-FALP) techniques which were developed in our laboratory. Part of the overall programme is supported by a grant... flowing afterglow / Langmuir probe (FALP) techniques. Using these techniques, rate coefficients and ion products of reactions can be determined in many

  9. Ionic Reactions of Atmospheric Importance.

    DTIC Science & Technology

    1983-11-30

    Flow Tube (SIFT) and the Flowing Afterglow / Langmuir Probe (FALP) techniques which were developed in our...recombination, electron-ion recombination and electron attachment. Such studies are possible using the flowing afterglow / Langmuir probe (FALP) apparatus...wi:hin the temperature range 200-600K, using a flowing afterglow / Langmuir probe apparatu, a,(O) is found to vary as -T - 7 in close accord with

  10. Observation of Thermal Electron Detachment from Cyclo-C4F8 in FALP experiments

    DTIC Science & Technology

    1994-01-01

    unlimited The methodology for use of a flowing afterglow - Langmuir probe apparatus to measure thermal electron detachment rate coefficients is...Abstract The methodology for use ofa flowing afterglow Langmuir probe apparatus to measure thermal electron detachment rate coefficients is described...technique [3,4], and a recent one summarizes the past measurements The flowing afterglow - Langmuir probe and describes new work in which both the gas

  11. Ion and Electron Interactions at Thermal and Suprathermal Energies

    DTIC Science & Technology

    1990-09-01

    flow drift tube (VT-SIFDT) and the variable-temperature flowing afterglow / Langmuir probe (VT-FALP...reactions. All these reaction processes can be studied using our selected ion flow drift tube (SIFDT) and Langmuir probe / flowing afterglow (FALP...Editors J.B.A. Mitchell and S.L. Guberman, World Scientific Publishing, (1989) 7) Development of the Flowing Afterglow / Langmuir Probe Technique

  12. GRB Discoveries with Swift

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2008-01-01

    This brief presentation presents Swift Observatory recordings of gamma ray burst (GRB) activity. Long and short GRBs and afterglows are highlighted. Recordings of GRB emission, afterglow, optical/IR brightness, and flux density are presented. The time structure and current status of short GRB structures is also included.

  13. Global Properties of X-Ray Flashes and X-Ray-Rich GRBs Observed by Swift

    NASA Technical Reports Server (NTRS)

    Sakamoto, T.; Yamazaki, R.; Cummings, J.; Krimm, H.; Parsons, A.; Hullinger, D.; Barbier, L.; Fenimore, E.; Markwardt, C.; Tueller, J.; Sato, G.; Barthelmy, S.; Gehrels, N.; Palmer, D.

    2007-01-01

    We describe and discuss the spectral and temporal characteristics of the prompt emission and X-ray afterglow emission of X-ray flashes (XRFs) detected and observed by Swift between December 2005 and September 2006. We compare these characteristics to a sample of X-ray rich gamma-ray bursts (XRRs) and conventional classical gamma-ray bursts (C-GRBs)observed during the same period. We confirm the correlation between Epeak and fluence noted by others and find further evidence that XRFs and C-GRBs form a continuum. We also confirmed that our known redshift samples are consistent with the correlation between the peak energy (Epeak) and the isotropic radiated energy (Eiso), so called the Epeak-Eiso relation. The spectral properties of X-ray afterglows are similar to those of gamma-ray burst afterglows, but the temporal properties of the two classes are quite different. We found that the light curves of C-GRBs afterglow show a break to steeper indices (shallow-to-steep break) at much earlier times than do XRF afterglows. Moreover, the overall luminosity of X-ray afterglows of XRFs are systematically smaller by a factor of two or more compared with that of C-GRBs. These distinct differences in the X-ray afterglow between XRFs and C-GRBs are key to understanding not only a mysterious shallow-to-steep phase in the X-ray afterglow but also the unique nature of XRFs.

  14. IDENTIFYING THE LOCATION IN THE HOST GALAXY OF THE SHORT GRB 111117A WITH THE CHANDRA SUBARCSECOND POSITION

    SciTech Connect

    Sakamoto, T.; Troja, E.; Aoki, K.; Guiriec, S.; Barthelmy, S. D.; Im, M.; Jeon, Y.; Leloudas, G.; Malesani, D.; De Ugarte Postigo, A.; Andersen, M. I.; Melandri, A.; D'Avanzo, P.; Urata, Y.; Xu, D.; Gorosabel, J.; Sanchez-Ramirez, R.; Briggs, M. S.; Foley, S.; and others

    2013-03-20

    We present our successful Chandra program designed to identify, with subarcsecond accuracy, the X-ray afterglow of the short GRB 111117A, which was discovered by Swift and Fermi. Thanks to our rapid target of opportunity request, Chandra clearly detected the X-ray afterglow, though no optical afterglow was found in deep optical observations. The host galaxy was clearly detected in the optical and near-infrared band, with the best photometric redshift of z=1.31{sub -0.23}{sup +0.46} (90% confidence), making it one of the highest known short gamma-ray burst (GRB) redshifts. Furthermore, we see an offset of 1.0 {+-} 0.2 arcsec, which corresponds to 8.4 {+-} 1.7 kpc, between the host and the afterglow position. We discuss the importance of using Chandra for obtaining subarcsecond X-ray localizations of short GRB afterglows to study GRB environments.

  15. Stationary afterglow measurements of the temperature dependence of the electron–ion recombination rate coefficients of {{\\rm{H}}}_{2}{{\\rm{D}}}^{+} and {{HD}}_{2}^{+} in He/Ar/H2/D2 gas mixtures at T = 80–145 K 

    NASA Astrophysics Data System (ADS)

    Plašil, Radek; Dohnal, Petr; Kálosi, Ábel; Roučka, Štěpán; Johnsen, Rainer; Glosík, Juraj

    2017-03-01

    We report measurements of the binary and ternary recombination rate coefficients of deuterated isotopologues of {{{H}}}3+. A cavity ring-down absorption spectrometer was used to monitor the fractional abundances of {{{H}}}3+, {{{H}}}2{{{D}}}+, {{HD}}2+ and {{{D}}}3+ during the decay of a plasma in He/Ar/{{{H}}}2/{{{D}}}2 mixtures. A dependence of the measured effective recombination rate coefficients on the helium buffer gas density was observed and hence both the binary and the ternary recombination rate coefficients for {{{H}}}2{{{D}}}+ and {{HD}}2+ were obtained in the temperature range 80–145 K.

  16. Experimental data for new fire-retardant materials

    NASA Technical Reports Server (NTRS)

    Supkis, D. E.

    1977-01-01

    Report contains evaluations of flammability and physical properties of twenty-four upholstery and furnishing materials, such as those used in commercial aircraft. Data presented include degradation upon heating, limited oxygen indices, smoke generation, flammability afterglow, and char length.

  17. The Effect of Magnetic Fields on Gamma-Ray Bursts Inferred from Multi-Wavelength Observations of the Bursts of 23 January 1999

    NASA Technical Reports Server (NTRS)

    Galama, T. J.; Briggs, M. S.; Wijers, R. A. M. J.; Vreeswijk, P. M.; Rol, E.; Band, D.; vanParadijs, J.; Kouveliotou, C.; Preece, R. D.; Bremer, M.

    1999-01-01

    Gamma-ray bursts (GRBs) are thought to arise when an extremely relativistic outflow of particles from a massive explosion (the nature at which is still unclear) interacts with material surrounding the site of the explosion. Observations of the evolving changes in emission at many wavelengths allow us to investigate the origin of the photons, and so potentially determine the nature of the explosion. Here we report the results of gamma-ray, optical, infrared, submillimeter, millimeter and radio observations of the burst ORB990123 and its afterglow. Our interpretation of the data indicates that the initial and afterglow emissions are associated with three distinct regions in the fireball. The peak flux of the afterglow, one day after the burst, has a lower frequency than observed for other bursts; this explains the short-lived radio emission. We suggest that the differences between bursts reflect variations in the magnetic-field strength in the afterglow-emitting regions.

  18. FLEX Test Point Video

    NASA Video Gallery

    Test #1 - Droplet diameter of 4 mm, with no support fiber. Droplet deployment was successful with a brief burn before radiative extinction. An afterglow from condensing vapor cloud and scattered ba...

  19. Recent Progress on GRBs with Swift

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Cannizzo, J. K.

    2010-01-01

    We are in an exciting period of discovery for gamma-ray bursts. The Swift observatory is detecting 100 bursts per year, providing arcsecond localizations and sensitive observations of the prompt and afterglow emission. In addition, rapid-response telescopes on the ground have new capabilities to study optical emission during the prompt phase and spectral signatures of the host galaxies. The combined data set is enabling great advances in our understanding of GRBs including afterglow physics, short burst origin, and supernova physics.

  20. Electron-temperature dependence of the recombination of H3O+(H2O)n ions with electrons

    NASA Technical Reports Server (NTRS)

    Johnsen, R.

    1993-01-01

    The T(e) dependence of the recombination of H3O+(H2O)n cluster-ions with electrons has been measured in an afterglow experiment in which the electrons were heated by a radio-frequency electric field. The recombination coefficients were found to vary with T(e) as about T(e) exp -1/2 in better agreement with theoretical expectations than earlier results of microwave-afterglow measurements.

  1. BOOTES and GTC observations of cosmic gamma-ray bursts and their progenitors

    NASA Astrophysics Data System (ADS)

    Castro-Tirado, Alberto J.

    2016-07-01

    We will summarize the follow-up observations of gamma-ray bursts performed worldwide by the BOOTES Network of robotic telescopes (with some of the data being contemporaneous to the prompt emission) leading to the discovery of many afterglows. Complementary data has been also obtained by the 10.4m GTC telescope in La Palma (mainly spectroscopy), with one of them being the highest extinguished afterglow detected to date.

  2. Atomic Processes Relevant to Antimatter Fuel Production and Storage

    DTIC Science & Technology

    1994-05-31

    Afterglow Langmuir Probe ) experiment that indicated that the rate was in fact much smaller, (ɚ x 10o cm3s’). They argued that their experiment...were vibrationally excited. This finding contradicts however, recent results from afterglow experiments (see below) and it was surmised that this...the room temperature rate coefficient had a value of about I 2 x 10V cm3sŕ. In 1983 however, Adams et al.9 published the results of a FALP ( Flowing

  3. Advanced Concept for Air Data System using EBF and Lidar

    DTIC Science & Technology

    2007-06-01

    Langmuir probes o Optical detection of afterglow The Doppler shift technique is quite straightforward by simply analysing the Doppler shift...EBF in a windtunnel - Visualisation of the electron beam and exploitation of its afterglow to visualise a Mach 10 flow around the ESA EXPERT...studies. Actually, there is a renewal of interest in extending the technique to higher densities and to probe CO/CO2 flows (Mars atmosphere studies

  4. GRACE Collaboration in the Swift Era

    NASA Technical Reports Server (NTRS)

    Kouveliotou, C.

    2004-01-01

    I will describe the structure and major discoveries of the Gamma-Ray Afterglow Collaboration at ESO, formed by several European Countries to perform GRB follow up observations using the European Southern Observatory (ESO) ground-based facilities in Chile. I represent the USA-UK node of GRACE. I will also describe a newly funded effort through the Swift GO program aiming at forming a Joint Afterglow NETwork (JANET) using members of the American Association of Variable Star Observers (AAVSO).

  5. How Special Are Dark Gamma-Ray Burst: A Diagnostic Tool

    NASA Technical Reports Server (NTRS)

    Rod, Evert; Wiers, Ralph A. M. J.; Kouveliotou, Chryssa; Kaper, Lex; Kaneko, Yuki; Kaper, Lex

    2005-01-01

    We present here a comprehensive study of the optical/near-infrared (IR) upper limits for gamma-ray bursts that have an X-ray afterglow. We have extrapolated the X-ray afterglows to optical wavelengths based on the physics of the fireball blast wave model and compared these results with optical upper limits for a large sample of bursts. We find a small set of only three bursts out of a sample of 20 for which the upper limits are not compatible with their X-ray afterglow properties within the context of any blast wave model. This sparse sample does not allow us to conclusively determine the cause of this optical/near-IR deficit. Extinction in the host galaxy is a likely cause, but high redshifts and different afterglow mechanisms might also explain the deficit in some cases. We note that the three bursts appear to have higher than average gamma-my peak fluxes. In a magnitude versus time diagram the bursts are separated from the majority of bursts with a detected optical/near-IR afterglow. However, two gamma- ray bursts with an optical afterglow (one of which is highly reddened) also fall in this region with dark bursts, making it likely that dark bursts are at the faint end of the set of optically detected bursts, and therefore the dark bursts likely form a continuum with the bursts with a detected optical afterglow. Our work provides a useful diagnostic tool for follow-up observations for potentially dark bursts; applied to the events detected with the Swift satellite, it will significantly increase our sample of truly dark bursts and shed light upon their nature. Subject headings: dust, extinction - gamma rays: bursts Online material: machine-readable tables

  6. A complete reference of the analytical synchrotron external shock models of gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Gao, He; Lei, Wei-Hua; Zou, Yuan-Chuan; Wu, Xue-Feng; Zhang, Bing

    2013-12-01

    Gamma-ray bursts are most luminous explosions in the universe. Their ejecta are believed to move towards Earth with a relativistic speed. The interaction between this "relativistic jet" and a circumburst medium drives a pair of (forward and reverse) shocks. The electrons accelerated in these shocks radiate synchrotron emission to power the broad-band afterglow of GRBs. The external shock theory is an elegant theory, since it invokes a limit number of model parameters, and has well predicted spectral and temporal properties. On the other hand, depending on many factors (e.g. the energy content, ambient density profile, collimation of the ejecta, forward vs. reverse shock dynamics, and synchrotron spectral regimes), there is a wide variety of the models. These models have distinct predictions on the afterglow decaying indices, the spectral indices, and the relations between them (the so-called "closure relations"), which have been widely used to interpret the rich multi-wavelength afterglow observations. This review article provides a complete reference of all the analytical synchrotron external shock afterglow models by deriving the temporal and spectral indices of all the models in all spectral regimes, including some regimes that have not been published before. The review article is designated to serve as a useful tool for afterglow observers to quickly identify relevant models to interpret their data. The limitations of the analytical models are reviewed, with a list of situations summarized when numerical treatments are needed.

  7. Identifying the Location in the Host Galaxy of Short GRB 1111l7A with the Chandra Sub- Arcsecond Position

    NASA Technical Reports Server (NTRS)

    Sakamoto, Takanori; Troja, E.; Aoki, K.; Guiriec, S.; Im, M.; Leloudas, G.; Malesani, D.; Melandri, A.; deUgartePostigo, A.; Urata, Y.; Xu, D.; DAvanzo, P.; Gorosabel, J.; Anderson, M. I.; Fynbo, J. P. U.; Aoki, K.; Sanchez-Ramirez, R.

    2012-01-01

    We present our successful program using Chandra for identifying the X-ray afterglow with sub-arcsecond accuracy for the short GRB 111117A d iscovered by Swift and Fermi. Thanks to our rapid target of opportuni ty request, Chandra clearly detected the X-ray afterglow, whereas no optical afterglow was found in deep optical observations. Instead, we clearly detect the host galaxy in optica; and also in near-infrared b ands. We found that the best photometric redshift fitofthe host is z = 1.31:(+0.46/-0.23) (90% confidence), making it one of the highest redshift short GRBs. Furthermore, we see an offset of 1.0+/-O.2 arcseco nds, which corresponds to 8.4+/-1.7 kpc aSBuming z= 1.31, between the host and the afterglow position. We discuss the importance of using Chandra for obtaining sub-arcsecond localization of the afterglow in X -rays for short GRBs to study GRB environments in great detail.

  8. The Swift X-Ray Te1escope: Status and Performance

    NASA Technical Reports Server (NTRS)

    Burrows, David N.; Kennea, J.A.; Abbey, A.F.; Beardmore, A.; Campana, S.; Capalbi, M.; Chincarini, G.; Cusumano, G.; Evans, P.A.; Hill, J.E.; Giommi, P.; Goad, M.; Godet, O.; Moretti, A.; Morris, D.C.; Osborne, J.P,; Pagani, C.; Page, K.L.; Perri, M.; Racusin, J.; Romano, P.; Starling, R.L.C.; Tagliaferri, G.; Tamburelli, F.; Tyler, L.G.

    2007-01-01

    We present science highlights and performance from the Swift X-ray Telescope (XRT), which was launched on November 20,2004. The XRT covers the 0.2-10 keV band, and spends most of its time observing gamma-ray burst (GRB) afterglows, though it has also performed observations of many other objects. By mid-August 2007, the XRT had observed over 220 GRB afterglows, detecting about 96% of them. The XRT positions enable followup ground-based optical observations, with roughly 60% of the afterglows detected at optical or near IR wavelengths. Redshifts are measured for 33% of X-ray afterglows. Science highlights include the discovery of flaring behavior at quite late times, with implications for GRB central engines; localization of short GRBs, leading to observational support for compact merger progenitors for this class of bursts; a mysterious plateau phase to GRB afterglows; as well as many other interesting observations such as X-ray emission from comets, novae, galactic transients, and other objects.

  9. Probing the complex environments of GRB host galaxies and intervening systems: high resolution spectroscopy of GRB050922C

    NASA Astrophysics Data System (ADS)

    Piranomonte, S.; Vergani, S.; Fiore, F.; D'Elia, V.; Krongold, Y.; Nicastro, F.; Stella, L.

    2009-05-01

    We use high resolution spectroscopic observations of the afterglow of GRB050922C, in order to investigate the environment of gamma ray bursts (GRBs) and the interstellar matter of their host galaxies. We found that, as for most high resolution spectra of GRBs, the spectrum of the afterglow of GRB050922C is complex. The detection of lines of neutral elements like MgI and the detection of fine-structure levels of the ions FeII, SiII and CII allows us to separate components in the GRB ISM along the line of sight. GRB afterglow spectra can be used to disentangle the contribution of the different parts of the GRB host galaxy and to study their properties.

  10. GRBs in the Era of Swift and Fermi

    NASA Technical Reports Server (NTRS)

    Racusin, Judy

    2011-01-01

    Utilizing both Swift and Fermi to study GRBs provides us with a unique broad spectral and temporal window into both prompt emission and afterglow studies. Swift has provided key information from GRB follow-up of LAT detected bursts) that has led to ground-based redshift measurements and afterglow broadband light curves and SEDs. We study the X-ray and optical afterglows of Fermi-LAT detected bursts in the context of the hundreds of GRBs discovered by Swift over the last 7 years) in order to better understand the origin of the high-energy gamma-rays. We also briefly describe the efforts to best facilitate joint Swift-Fermi observations. These initial results demonstrate the synergy between Swift and Fermi) and hint at the many interesting discoveries to come.

  11. Chameleon fragmentation

    SciTech Connect

    Brax, Philippe

    2014-02-01

    A scalar field dark energy candidate could couple to ordinary matter and photons, enabling its detection in laboratory experiments. Here we study the quantum properties of the chameleon field, one such dark energy candidate, in an ''afterglow'' experiment designed to produce, trap, and detect chameleon particles. In particular, we investigate the possible fragmentation of a beam of chameleon particles into multiple particle states due to the highly non-linear interaction terms in the chameleon Lagrangian. Fragmentation could weaken the constraints of an afterglow experiment by reducing the energy of the regenerated photons, but this energy reduction also provides a unique signature which could be detected by a properly-designed experiment. We show that constraints from the CHASE experiment are essentially unaffected by fragmentation for φ{sup 4} and 1/φ potentials, but are weakened for steeper potentials, and we discuss possible future afterglow experiments.

  12. "Short, Hard Gamma-Ray Bursts - Mystery Solved?????"

    NASA Technical Reports Server (NTRS)

    Parsons, A.

    2006-01-01

    After over a decade of speculation about the nature of short-duration hard-spectrum gamma-ray bursts (GRBs), the recent detection of afterglow emission from a small number of short bursts has provided the first physical constraints on possible progenitor models. While the discovery of afterglow emission from long GRBs was a real breakthrough linking their origin to star forming galaxies, and hence the death of massive stars, the progenitors, energetics, and environments for short gamma-ray burst events remain elusive despite a few recent localizations. Thus far, the nature of the host galaxies measured indicates that short GRBs arise from an old (> 1 Gyr) stellar population, strengthening earlier suggestions and providing support for coalescing compact object binaries as the progenitors. On the other hand, some of the short burst afterglow observations cannot be easily explained in the coalescence scenario. These observations raise the possibility that short GRBs may have different or multiple progenitors systems. The study of the short-hard GRB afterglows has been made possible by the Swift Gamma-ray Burst Explorer, launched in November of 2004. Swift is equipped with a coded aperture gamma-ray telescope that can observe up to 2 steradians of the sky and can compute the position of a gamma-ray burst to within 2-3 arcmin in less than 10 seconds. The Swift spacecraft can slew on to this burst position without human intervention, allowing its on-board x ray and optical telescopes to study the afterglow within 2 minutes of the original GRB trigger. More Swift short burst detections and afterglow measurements are needed before we can declare that the mystery of short gamma-ray burst is solved.

  13. Heterogeneity in Short Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Norris, Jay P.; Gehrels Neil; Scargle, Jeffrey D.

    2011-01-01

    We analyze the Swift/BAT sample of short gamma-ray bursts, using an objective Bayesian Block procedure to extract temporal descriptors of the bursts' initial pulse complexes (IPCs). The sample comprises 12 and 41 bursts with and without extended emission (EE) components, respectively. IPCs of non-EE bursts are dominated by single pulse structures, while EE bursts tend to have two or more pulse structures. The medians of characteristic timescales - durations, pulse structure widths, and peak intervals - for EE bursts are factors of approx 2-3 longer than for non-EE bursts. A trend previously reported by Hakkila and colleagues unifying long and short bursts - the anti-correlation of pulse intensity and width - continues in the two short burst groups, with non-EE bursts extending to more intense, narrower pulses. In addition we find that preceding and succeeding pulse intensities are anti-correlated with pulse interval. We also examine the short burst X-ray afterglows as observed by the Swift/XRT. The median flux of the initial XRT detections for EE bursts (approx 6 X 10(exp -10) erg / sq cm/ s) is approx > 20 x brighter than for non-EE bursts, and the median X-ray afterglow duration for EE bursts (approx 60,000 s) is approx 30 x longer than for non-EE bursts. The tendency for EE bursts toward longer prompt-emission timescales and higher initial X-ray afterglow fluxes implies larger energy injections powering the afterglows. The longer-lasting X-ray afterglows of EE bursts may suggest that a significant fraction explode into more dense environments than non-EE bursts, or that the sometimes-dominant EE component efficiently p()wers the afterglow. Combined, these results favor different progenitors for EE and non-EE short bursts.

  14. The influence of Nd3+ in CaAl2O4:Eu2+,Nd3+ phosphor fabricated by combustion synthesis

    NASA Astrophysics Data System (ADS)

    Yang, Zhiping; Yang, Yong; Li, Xingmin; Li, Xu; Liu, Chong; Feng, Jianwei

    2005-01-01

    Eu2+, Nd3+ co-doped calcium aluminate (CaAl2O4) phosphor with high brightness and long afterglow were fabricated by urea-nitrate solution combustion synthesis at 600°C. The phosphor powder of combustion synthesis were generally more homogeneous and had fewer impurity than phosphor fabricated by conventional solid-state methods, the character could conduce to obtain more exact data. The excitation and emission spectrum indicated that there waxs only one luminescence center Eu2+, both of the characteristic spectrums of Eu3+ and Nd3+ weren't discovered. As a secondary activator, Nd3+ could make remarkable influence on the afterglow of phosphor. From altering the moral ratio of Eu2+ and Nd3+, the lasting time of afterglow and thermoluminescence were studied respectively, when Nd3+ wasn't appended, the intensity of initial brightness could compared with other materials which had different ratio of Eu2+ and Nd3+, however the brightness of afterglow decayed rapidly, the lasting time and brightness of afterglow were improved with reduce the radio of Eu2+ and Nd3+, while the ratio achieved some value, the lasting time of afterglow become shorten with the reduce of ratio of Eu2+ and Nd3+. Moreover the depth of trap was calculated from the parameter of thermoluminescence. However, the emission spectrum and XRD patterns didn't change obviously with the altering ratio of Eu2+ and Nd3+. It showed that the little amount of doped rear earth ions (Eu2+ and Nd3+) had almost no effect on the CaAl2O4 phase composition. Based on these conclusions, the model of the luminescence process of CaAl2O4:Eu2+, Nd3+ was built.

  15. HETEROGENEITY IN SHORT GAMMA-RAY BURSTS

    SciTech Connect

    Norris, Jay P.; Gehrels, Neil

    2011-07-01

    We analyze the Swift/BAT sample of short gamma-ray bursts, using an objective Bayesian Block procedure to extract temporal descriptors of the bursts' initial pulse complexes (IPCs). The sample is comprised of 12 and 41 bursts with and without extended emission (EE) components, respectively. IPCs of non-EE bursts are dominated by single pulse structures, while EE bursts tend to have two or more pulse structures. The medians of characteristic timescales-durations, pulse structure widths, and peak intervals-for EE bursts are factors of {approx}2-3 longer than for non-EE bursts. A trend previously reported by Hakkila and colleagues unifying long and short bursts-the anti-correlation of pulse intensity and width-continues in the two short burst groups, with non-EE bursts extending to more intense, narrower pulses. In addition, we find that preceding and succeeding pulse intensities are anti-correlated with pulse interval. We also examine the short burst X-ray afterglows as observed by the Swift/X-Ray Telescope (XRT). The median flux of the initial XRT detections for EE bursts ({approx}6x10{sup -10} erg cm{sup -2} s{sup -1}) is {approx}>20x brighter than for non-EE bursts, and the median X-ray afterglow duration for EE bursts ({approx}60,000 s) is {approx}30x longer than for non-EE bursts. The tendency for EE bursts toward longer prompt-emission timescales and higher initial X-ray afterglow fluxes implies larger energy injections powering the afterglows. The longer-lasting X-ray afterglows of EE bursts may suggest that a significant fraction explode into denser environments than non-EE bursts, or that the sometimes-dominant EE component efficiently powers the afterglow. Combined, these results favor different progenitors for EE and non-EE short bursts.

  16. KSC-04PD-2111

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. Technician Grace Miller-Swales does touch-up work on the Swift spacecraft in Hangar AE at Cape Canaveral Air Force Station. Swift is wrapped with blankets to provide thermal stability during the mission. Swift is a first- of-its-kind multi-wavelength observatory dedicated to the study of gamma-ray burst (GRB) science. Its three instruments will work together to observe GRBs and afterglows in the gamma-ray, X-ray, ultraviolet and optical wavebands. The most comprehensive study of GRB afterglows to date, Swift is expected to observe more than 200 gamma-ray bursts during its 2-year mission.

  17. Recombination of N4(+) ions with electrons

    NASA Technical Reports Server (NTRS)

    Cao, Y. S.; Johnsen, R.

    1991-01-01

    Using a modified high-pressure-afterglow/mass spectrometer apparatus similar to that described by Lee and Johnsen (1989), spectroscopic observations of afterglow helium plasmas, with N2 as a minor additive, were carried out in order to verify the mechanism suggested by Bates (1991) for dissociative recombination of electrons with N4(+) ions. It was found that dissociative recombination of electrons with N4(+) ions results in the formation of N2 molecules in the C 3Pi(u) (v = 0,1) state, with the recombination rate coefficient of (2.6 +/- 0.3) x 10 exp -6 cu cm/sec at 300 K.

  18. Collisional Excitation and Ionization

    DTIC Science & Technology

    1979-09-30

    and Brocklehurst [36] have discussed the form of dimer cations and from electron spin resonance experiments [37] havc concluded that the benzene dimcr...temperature (’K) Reference F, 7.5x 10"s Flowing afterglow -500 4 C! 2 3. 1 x 10"O Electron cyclotron 293 5 resonance hJr 2 0.82 x 10Ŗ Static afterglow 296...NO’(.\\’XA’) are to be 6,1 is unity if spin orbital j is occupied in configuration interpreted as estimates of the N2O + c resonance en- k for state s

  19. Initial Results from Swift/uvot

    NASA Astrophysics Data System (ADS)

    Marshall, F. E.

    2008-09-01

    The UltraViolet/Optical Telescope on Swift is a 30-cm Richey-Cretien reflector that provides sub-arcsecond positions, light curves on time scales from minutes to days after a GRB, and spectra covering 160 - 700 nm. UVOT is detecting optical afterglows from ~67% of rapidly observed long GRBs that have little extinction in the Milky Way. We consider possible reasons for the non-detections. UVOT is also producing remarkable results on the evolution of GRB afterglows including GRB060218/SN2006aj as well as the evolution of young supernovae.

  20. Vibrational Product States from Reactions of CN(-) with the Hydrogen Halides and Hydrogen Atoms,

    DTIC Science & Technology

    1981-01-15

    not possible for the (00n) levels of CO2 . A. The flowing afterglow apparatus The ion-molecule reactions which are the subject of The flowing afterglow...51: 0. 44: 0. 051. Errors for these values are ± 10%. atomic molecule about which a great deal is known, CO2 From this we see that when the extra...Total 2J. Berkowitz, W. A. Chupka, and T. A. Walter, J. Chem. Reaction Filter intensity emission Phys. 50, 1497 (1968). "’D. R. Stull and H. Prophet

  1. THE ORTHOGONAL GAMMA-RAY BURST MODEL

    SciTech Connect

    Contopoulos, Ioannis; Pugliese, Daniela; Nathanail, Antonios

    2014-01-01

    We explore the analogy between a rotating magnetized black hole and an axisymmetric pulsar and derive the black hole's electromagnetic spindown after its formation in the core collapse of a supermassive star. The spindown shows two characteristic phases: an early Blandford-Znajek phase that lasts a few hundred seconds and a late pulsar-like afterglow phase that lasts much longer. During the first phase, the spindown luminosity decreases almost exponentially, whereas during the afterglow phase it decreases as t {sup –a} with 1 ≲ a ≲ 1.5. We associate our findings with long duration gamma-ray bursts and compare them with observations.

  2. Investigating the Impact of Optical Selection Effects on Observed Rest-frame Prompt GRB Properties

    NASA Astrophysics Data System (ADS)

    Turpin, D.; Heussaff, V.; Dezalay, J.-P.; Atteia, J.-L.; Klotz, A.; Dornic, D.

    2016-11-01

    Measuring gamma-ray burst (GRB) properties in their rest frame is crucial for understanding the physics at work in GRBs. This can only be done for GRBs with known redshifts. Since redshifts are usually measured from the optical spectrum of the afterglow, correlations between prompt and afterglow emissions may introduce biases into the distribution of the rest-frame properties of the prompt emission, especially considering that we measure the redshift of only one-third of Swift GRBs. In this paper, we study the optical flux of GRB afterglows and its connection to various intrinsic properties of GRBs. We also discuss the impact of the optical selection effect on the distribution of rest-frame prompt properties of GRBs. Our analysis is based on a sample of 90 GRBs with good optical follow-up and well-measured prompt emission. Seventy-six of them have a measure of redshift and 14 have no redshift. We compare the rest-frame prompt properties of GRBs with different afterglow optical fluxes in order to check for possible correlations between the promt properties and the optical flux of the afterglow. The optical flux is measured two hours after the trigger, which is a typical time for the measure of the redshift. We find that the optical flux of GRB afterglows in our sample is mainly driven by their optical luminosity and depends only slightly on their redshift. We show that GRBs with low and high afterglow optical fluxes have similar E {}{{pi}}, E {}{{iso}}, and L {}{{iso}}, indicating that the rest-frame distributions computed from GRBs with a redshift are not significantly distorted by optical selection effects. However, we found that the {T}90{rest} distribution is not immune to optical selection effects, which favor the selection of GRBs with longer durations. Finally, we note that GRBs well above the E {}{{pi}}-E {}{{iso}} relation have lower optical fluxes and we show that optical selection effects favor the detection of GRBs with bright optical afterglows located

  3. Alpenglow: A signature for chameleons in axionlike particle search experiments

    SciTech Connect

    Ahlers, M.; Lindner, A.; Ringwald, A.; Schrempp, L.; Weniger, C.

    2008-01-01

    We point out that chameleon field theories might reveal themselves as an afterglow effect in axionlike particle search experiments due to chameleon-photon conversion in a magnetic field. We estimate the parameter space which is accessible by currently available technology and find that afterglow experiments could constrain this parameter space in a way complementary to gravitational and Casimir force experiments. In addition, one could reach photon-chameleon couplings which are beyond the sensitivity of common laser polarization experiments. We also sketch the idea of a Fabry-Perot cavity with chameleons which could increase the experimental sensitivity significantly.

  4. Accountability for Better Results ? A National Imperative for Higher Education

    ERIC Educational Resources Information Center

    State Higher Education Executive Officers, 2005

    2005-01-01

    For over fifty years, speaker after speaker ? university presidents, business leaders, Presidents of the United States ? have praised our system of higher education as the finest in the world,but even as we bask in the afterglow of past achievements a starker reality is emerging on the horizon. For the first time in decades the United States no…

  5. Late time observations of candidate high-z GRBs

    NASA Astrophysics Data System (ADS)

    Burlon, Davide; Gaensler, Bryan; Murphy, Tara; Hancock, Paul; Ghirlanda, Giancarlo; Salvaterra, Ruben; Ghisellini, Gabriele; Tagliaferri, Gianpiero

    2014-04-01

    This is a targeted proposal to detect late time radio afterglow of a sample of potentially high redshift gamma ray bursts (GRBs). Our targets have been selected from detections of the the last two years by the Swift/BAT telescope. Radio observations play a crucial role in determining the energetics of the GRB explosion, and will therefore directly point towards exceptional progenitors.

  6. Small-Angle Scattering of X-Rays from Extragalactic Sources by Dust in Intervening Galaxies

    NASA Astrophysics Data System (ADS)

    Miralda-Escudé, Jordi

    1999-02-01

    Gamma-ray bursts are now known to be a cosmological population of objects, which are often accompanied by X-ray and optical afterglows. The total energy emitted in the afterglow can be similar to the energy radiated in the gamma-ray burst itself. If a galaxy containing a large column density of dust is near the line of sight to a gamma-ray burst, small-angle scattering of the X-rays due to diffraction by the dust grains will give rise to an X-ray echo of the afterglow. A measurement of the angular size of the echo at a certain time after the afterglow is observed yields a combination of the angular diameter distances to the scattering galaxy and the gamma-ray burst that can be used to constrain cosmological models in the same way as a time delay in a gravitational lens. The scattering galaxy will generally cause gravitational lensing as well, and this should modify the shape of the X-ray echo from a circular ring. The main difficulty in detecting this phenomenon is the very low flux expected for the echo. The flux can be increased when the gamma-ray burst is highly magnified by gravitational lensing, or when the deflecting galaxy is at low redshift. X-ray echoes of continuous (but variable) sources, such as quasars, may also be detectable with high-resolution instruments and would allow similar measurements.

  7. A HOT COCOON IN THE ULTRALONG GRB 130925A: HINTS OF A POPIII-LIKE PROGENITOR IN A LOW-DENSITY WIND ENVIRONMENT

    SciTech Connect

    Piro, Luigi; Troja, Eleonora; Kidd, Lauren A.; Ghisellini, Gabriele; Ricci, Roberto; Bannister, Keith; Fiore, Fabrizio; Piranomonte, Silvia; Wieringa, Mark H.

    2014-08-01

    GRB 130925A is a peculiar event characterized by an extremely long gamma-ray duration (≈7 ks), as well as dramatic flaring in the X-rays for ≈20 ks. After this period, its X-ray afterglow shows an atypical soft spectrum with photon index Γ ∼ 4, as observed by Swift and Chandra, until ≈10{sup 7} s, when XMM-Newton observations uncover a harder spectral shape with Γ ∼ 2.5, commonly observed in gamma-ray burst (GRB) afterglows. We find that two distinct emission components are needed to explain the X-ray observations: a thermal component, which dominates the X-ray emission for several weeks, and a non-thermal component, consistent with a typical afterglow. A forward shock model well describes the broadband (from radio to X-rays) afterglow spectrum at various epochs. It requires an ambient medium with a very low-density wind profile, consistent with that expected from a low-metallicity blue supergiant (BSG). The thermal component has a remarkably constant size and a total energy consistent with those expected by a hot cocoon surrounding the relativistic jet. We argue that the features observed in this GRB (its ultralong duration, the thermal cocoon, and the low-density wind environment) are associated with a low metallicity BSG progenitor and, thus, should characterize the class of ultralong GRBs.

  8. Thermoluminescence of β-Irradiated ZnS-ZnO Phosphors

    NASA Astrophysics Data System (ADS)

    Cruz-Vázquez, C.; Bernal, R.; Burruel-Ibarra, S. E.; Cota-Valenzuela, E.; Brown, F.; Grijalva-Monteverde, H.; Castaño, V. M.

    2015-10-01

    ZnS-ZnO thermoluminescent phosphors have been synthesized by a low-cost chemical method. They exhibit a thermoluminescence response increasing linearly as a function of β-irradiation dose, from 25 Gy to 1600 Gy, without saturation. The glow curves indicate that these phosphors could be useful for both thermoluminescence and afterglow dosimetry.

  9. Gamma-Ray Bursts, Collisionless Shocks and Synthetic Spectra

    NASA Astrophysics Data System (ADS)

    Hededal, Christian

    2005-06-01

    The radiation from afterglows of gamma-ray bursts (GRB) is generated in collisionless plasma shocks. The two main ingredients behind the radiation are high-energy, non-thermal electrons and a strong magnetic field. I argue that in order to make the right conclusions about gamma-ray burst and afterglow parameters from observations, it is crucial to have a firm understanding of the microphysics of collisionless shock. I present the results of self-consistent, three-dimensional particle-in-cell computational simulations of the collision of weakly magnetized plasma shells: The experiments show how a plasma instability generates a magnetic field in the shock. The field has strength up to percents of the equipartition value. The experiments also reveal a new, non-thermal electron acceleration mechanism that differs substantially from Fermi acceleration. Finally, I present the results from a new numerical tool that enables us to extract synthetic radiation spectra directly from the experiments. The preliminary results differ from synchrotron radiation but are consistent with GRB afterglow observations. I conclude that strong magnetic field generation, non-thermal particle acceleration and the emission of radiation that is consistent with GRB afterglow observations, are all unavoidable consequences of the collision between two relativistic plasma shells.

  10. ESA Gaia and GRBs

    SciTech Connect

    Hudec, Rene; Simon, Vojtech; Hudec, Lukas

    2008-05-22

    Albeit focusing on astrometry, the ESA Gaia space mission will also provide spectrophotometry for all objects down to mag 20 over 5 years operation period. Typically 50 to 200 measurements per object including optical counterparts of celestial high-energy sources can be expected during this time interval. Also optical afterglows and optical transients of GRBs can be detected and investigated this way.

  11. Synchrotron radiation and diffusive shock acceleration - A short review and GRB perspective

    SciTech Connect

    Karlica, Mile

    2015-12-17

    In this talk we present the sponge” model and its possible implications on the GRB afterglow light curves. “Sponge” model describes source of GRB afterglow radiation as fragmented GRB ejecta where bubbles move through the rarefied medium. In the first part of the talk a short introduction to synchrotron radiation and Fermi acceleration was presented. In the assumption that X-ray luminosity of GRB afterglow phase comes from the kinetic energy losses of clouds in ejecta medium radiated as synchrotron radiation we solved currently very simple equation of motion to find which combination of cloud and medium regime describes the afterglow light curve the best. We proposed for the first step to watch simple combinations of expansion regimes for both bubbles and surrounding medium. The closest case to the numerical fit of GRB 150403A with time power law index k = 1.38 is the combination of constant bubbles and Sedov like expanding medium with time power law index k = 1.25. Of course the question of possible mixture of variuos regime combinations is still open within this model.

  12. Radio and X-ray observations of the Ultra-long GRB 150518A

    NASA Astrophysics Data System (ADS)

    Johnson, Louis; Kamble, Atish; Margutti, Raffaella; Soderberg, Alicia Margarita; Supernova Forensics

    2016-01-01

    Gamma Ray Burst (GRB) 150518A, discovered on 2015 May 18 by the MAXI and KONUS-Wind satellites, lasted for about 1000s, making it an important addition to the recently established class of very long duration GRBs. We report on the JVLA radio observations of the afterglow of GRB 150518A. Additionally, we report the analysis of Xray afterglow observations by Swift-XRT. Multi-band light curves of the radio afterglow display an unusual, conspicuous rise around 10 days after the burst, possibly due to enhanced mass-loss from the progenitor in the final stages of evolution before the GRB. The X-ray afterglow spectrum is significantly soft (photon index Γx > 3) and heavily absorbed (NHx,i > 8 × 10^{21}/cm^2). These properties suggest peculiar behavior that is different from the predictions of the standard fireball model of GRBs. In the light of these properties, we compare different models of progenitors for very long duration GRBs. This work was supported in part by the NSF REU and DoD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

  13. Proceedings of Conference on Applications of Chemistry to Nuclear Weapons Effects (2nd). Held on 12-14 September 1972. Abstracts of Papers

    DTIC Science & Technology

    1974-12-23

    by the Defense Nuclear Agency C (DNA) -- formerly the Defense Atomic Support Agency--in cooperation with the N Air Force Cambridge Research...principal reactions in ionized air containing water vapor -------- 77 Recent flowing afterglow results on ionospheric ion-neutral reactions...Measurement of NO concentrations in excited air fromy-band emission ---------------------- 101 (* ) Applications of advanced photometric and image

  14. Long-Lasting Phosphorescence Properties of Pyrochlore La2Ti2O7:Pr3+ Phosphor

    NASA Astrophysics Data System (ADS)

    Chu, Ming-Hui; Jiang, Da-Peng; Zhao, Cheng-Jiu; Li, Bin

    2010-04-01

    The La2Ti2O7:Pr3+, which emits red color luminescence upon UV light excitation, is prepared by the conventional high-temperature solid-state method and its luminescent properties are systematically investigated. X-ray diffraction, photoluminescence, afterglow emission spectra and long-lasting phosphorescence (LLP) decay curves are used to characterize this phosphor. After irradiation by a 290-nm UV light for 3 min, the Pr3+-doped La2Ti2O7 phosphor emits intense red emitting afterglow from the 1 D2 → 3H4 transitions, and its afterglow can be seen with the naked eye in the dark clearly for more than 1 h after removal of the excitation source. The afterglow decay curve of the Pr3+-doped La2Ti2O7 phosphor contains a fast decay component and another slow decay one. The possible mechanism of this red light emitting LLP phosphor is also discussed based on the experimental results.

  15. Kinetic studies at room temperature of the cyanide anion CN - with cyanoacetylene (HC 3N) reaction

    NASA Astrophysics Data System (ADS)

    Carles, S.; Adjali, F.; Monnerie, C.; Guillemin, J.-C.; Le Garrec, J.-L.

    2011-01-01

    Rate coefficient of the cyanide anion (CN -) with cyanoacetylene (HC 3N) reaction, has been studied in gas phase at room temperature using a Flowing Afterglow Langmuir Probe - Mass Spectrometer (FALP-MS) apparatus. The rate constant for the CN - + HC 3N reaction is k = 4.8 × 10 -9 cm 3/s with an uncertainty of 30%.

  16. Merged Beam Studies into the Mechanisms of Hydrogen Molecular Ion Recombination

    DTIC Science & Technology

    1989-09-30

    of about xl0-8 cm 3sec- I at 300K in agreement with the original published values of Adams et al 2 ), measured using the Flowing Afterglow Langmuir ... Probe , (FALP), technique. Adams and Smith (3 ) have however recalibrated their apparatus and now claim that the rate coefficient for the recombination

  17. The dissociative recombination of ?

    NASA Astrophysics Data System (ADS)

    Laubé, S.; Lehfaoui, L.; Rowe, B. R.; Mitchell, J. B. A.

    1998-09-01

    The dissociative recombination rate coefficient for 0953-4075/31/18/016/img2 has been measured at 300 K using a flowing afterglow Langmuir probe-mass spectrometer apparatus. A value of 0953-4075/31/18/016/img3 has been found.

  18. Electron attachment to anthracene. A FALP measurement of the rate coefficient at room temperature

    NASA Astrophysics Data System (ADS)

    Canosa, A.; Parent, D. C.; Pasquerault, D.; Au; Gomet, J. C.; Laubé, S.; Rowe, B. R.

    1994-09-01

    The rate coefficient β for electron attachment to anthracene has been measured at room temperature using a flowing afterglow Langmuir probe mass spectrometer. A value of 1 × 10 -9 cm 3 s -1 (30% uncertainty) was found, indicating that an activation energy barrier might exist.

  19. Recombination studies in a He-Ar-H2 plasma

    NASA Astrophysics Data System (ADS)

    Glosík, J.; Plasil, R.; Pysanenko, A.; Novotný, O.; Hlavenka, P.; Macko, P.; Bánó, G.

    2005-01-01

    The recombination of H+3 ions with electrons has been studied in afterglow plasma in three different experiments. In two experiments, using the Variable Temperature Stationary Afterglow (VT-AISA) and the Variable Temperature Flowing Afterglow (VT-FALP) techniques, a decay of the electron number density was measured by an electrostatic Langmuir probe to determine the recombination rate coefficient. In the third experiment a near infrared Cavity Ring-Down Absorption Spectrometer (CRDS) was used to monitor the decay of the H+3 (v = 0) ion density during the afterglow. Measurements were carried out in helium buffer gas with small admixtures of argon and hydrogen at total pressures ranging from 150 up to 1200 Pa and at buffer gas temperatures ranging from 100 up to 330 K. In the experiments the partial number density of hydrogen was varied from 5 × 1010 up to 1 × 1016 cm-3 and for this broad range of hydrogen number densities effective recombination rate coefficients were obtained, which varied over three orders of magnitude from 2 × 10-9 cm3s-1 at [H2] = 5 × 1010 cm-3 up to 3 × 10-6 cm3s-1 at [H2] = 1 × 1016 cm-3. Using our experimental results we discuss possible mechanisms of recombination in hydrogen plasma in a very broad range of several parameters: buffer gas pressure, temperature, electron number density, hydrogen number density and internal excitation of recombining ions.

  20. Intumescent all-polymer multilayer nanocoating capable of extinguishing flame on fabric

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton fabric was treated with flame-retardant coatings composed of poly (sodium phosphate), PSP, which acts as the acid source, and poly (allylamine), PAAm, which is used as the blowing agent, prepared via layer-by-layer (LbL) assembly. By applying these thin coating on fabric, after-glow is elimi...

  1. Observations of Gamma-Ray Bursts by HETE-2

    NASA Technical Reports Server (NTRS)

    Kawai, N.; Matsuoka, M.; Yoshida, A.; Shirasaki, Y.; Ricker, G.; Doty, J.; Vanderspek, R.; Crew, G.; Villasenor, J.; Atteia, J.-L.; Fenimore, E. E.; Galassi, M.; Lamb, D. Q.; Graziani, C.; Hurley, K.; Jernigan, J. G.; Woosley, S.; Martel, F.; Monnelly, G.; Prigozhin, G.; Olive, J.-F.; Dezalay, J.P.; Boer, M.; Pizzichini, G.; Cline, T.

    2004-01-01

    The High Energy Transient Explorer 2 (HETE-2), launched in October 2000, is currently localizing gamma-ray bursts (GRBs) at a rate of approximately 20/yr, many in real time. As of August 2003, HETE-2 had localized 43 GRBs; 16 localizations had led to the detection of an X-ray, optical, or radio afterglows. The prompt position notification of HETE-2 enabled probing the nature of so-called "dark bursts" for which no optical afterglows were found despite of accurate localizations. In some cases, the optical afterglow was found to be intrinsically faint , and its flux declined rapidly. In another case, the optical emission was likely to be extinguished by the dust in the vicinity of the GRB source. The bright afterglows of GRB021004 and GRB030329 were observed in unprecedented details by telescopes around the world. Strong evidence for the association of long GRBs with the core-collapse supernovae was found. HETE-2 has localized almost as many X-ray rich GRBs as classical GRBs. The nature of the X-ray rich GRBs and X-ray flashes have been studied systematically with HETE-2, and they are found to have many properties in common with the classical GRBs, suggesting that they are a single phenomenon.

  2. Metal-atom fluorescence from the quenching of metastable rare gases by metal carbonyls

    SciTech Connect

    Hollingsworth, W.E.

    1982-11-01

    A flowing afterglow apparatus was used to study the metal fluorescence resulting from the quenching of metastable rare-gas states by metal carbonyls. The data from the quenching or argon, neon, and helium by iron and nickel carbonyl agreed well with a restricted degree of freedom model indicating a concerted bond-breaking dissociation.

  3. The Statistics of BAT-to-XRT Flux Ratio in GRB: Evidence for a Characteristic Value and its Implications

    NASA Astrophysics Data System (ADS)

    Kazanas, D.; Racusin, J. L.; Sultana, J.; Mastichiadis, A.

    2016-10-01

    We present the statistics of the luminosity ratio R between the prompt emission and the GRB afterglow plateau to show that R has a characteristic value 2000 close the proton/electron mass ratio as suggested by an earlier model of ours.

  4. Luminescent properties of long lasting phosphor Ca{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 2+}

    SciTech Connect

    Gong Yu; Wang Yuhua; Jiang Ziqiang; Xu Xuhui; Li Yanqin

    2009-09-15

    Long afterglow phosphors (Ca{sub 1-x}Eu{sub x}){sub 2}MgSi{sub 2}O{sub 7} (0.002 {<=} x {<=} 0.02) were prepared by solid-state reactions under a weak reductive atmosphere. X-ray diffraction pattern, photoluminescence spectra, decay curve, afterglow spectra and thermoluminescence curves were investigated. The phosphors showed two emission peaks when they were excited by 343 nm, due to two types of Eu{sup 2+} centers existing in the Ca{sub 2}MgSi{sub 2}O{sub 7} lattice. However, only one emission peak can be found in their afterglow spectra. Energy transfer between Eu{sup 2+} ions in inequivalent sites was found. A possible mechanism was presented and discussed. The afterglow decay time of Ca{sub 1.998}MgSi{sub 2}O{sub 7}:Eu{sub 0.002} was nearly 12.5 h which means it was a good long lasting phosphor.

  5. GRB070125: The First Long-Duration Gamma-Ray Burst in a Halo Environment

    NASA Technical Reports Server (NTRS)

    Bradley, Cenko S.; Fox, Derek B.; Penprase, Brian E.; Kulkarni, Shri R.; Price, Paul A.; Berger, Edo; Kulkarni, Shri R.; Harrison, Fiona A.; Gal-Yam, Avishay; Ofek, Eran O.; Rau, Arne; Chandra, Poonam; Frail, Dale A.; Kasliwal, Mansi M.; Schmidt, Brian P.; Soderberg, Alicia M.; Cameron, P. Brian; Roth, Kathy C.

    2007-01-01

    We present the discovery and high signal-to-noise spectroscopic observations of the optical afterglow of the long-duration gamma-ray burst GRB070125. Unlike all previously observed long-duration afterglows in the redshift range 0.5 < z < 2.0, we find no strong (rest-frame equivalent width W > 1.0 A) absorption features in the wavelength range 4000 - 10000 A. The sole significant feature is a weak doublet we identify as Mg 11 2796 (W = 0.18 +/- 0.02 A), 2803 (W = 0.08 +0I.-01 ) at z = 1.5477 +/- 0.0001. The low observed Mg II and inferred H I column densities are typically observed in galactic halos, far away from the bulk of massive star formation. Deep ground-based imaging reveals no host directly underneath the afterglow to a limit of R > 25.4 mag. Either of the two nearest blue galaxies could host GRB070125; the large offset (d >= 27 kpc) would naturally explain the low column density. To remain consistent with the large local (i.e. parsec scale) circum-burst density inferred from broadband afterglow observations, we speculate GRB070125 may have occurred far away from the disk of its host in a compact star-forming cluster. Such distant stellar clusters, typically formed by dynamical galaxy interactions, have been observed in the nearby universe, and should be more prevalent at z>l where galaxy mergers occur more frequently.

  6. A Bulk Comptonization Model for the Prompt GRM Emission

    NASA Technical Reports Server (NTRS)

    Kazanas, Demos; Mastichiadis, A.

    2010-01-01

    The "Supercritical Pile" is a very economical GRB model that provides for the efficient conversion of the energy stored in the protons of a Relativistic Blast Wave (RBW) into radiation and at the same time produces - in the prompt GRB phase, even in the absence of any particle acceleration - a spectral peak at energy approximately 1 MeV. We extend this model to include the evolution of the RBW Lorentz factor F and thus follow its spectral and temporal features into the early GRB afterglow stage. One of the novel features of the present treatment is the inclusion of the feedback of the GRB produced radiation on the evolution of Gamma with radius. This feedback and the presence of kinematic and dynamic thresholds in the model are sources of potentially very rich time evolution which we have began to explore. In particular, one can this way obtain afterglow light curves with steep decays followed by the more conventional flatter afterglow slopes, while at the same time preserving the desirable features of the model, i.e. the well defined relativistic electron source and radiative processes that produce the proper peak in the nu F(sub nu) spectra. In this note we present the results of a specific set of parameters of this model with emphasis on the multiwavelength prompt emission and transition to the early afterglow.

  7. The SKA View of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Burlon, D.; Ghirlanda, G.; van der Horst, A.; Murphy, T.; Wijers, R. A. M. J.; Gaensler, B.; Ghisellini, G.; Prandoni, I.

    2015-04-01

    Gamma-ray bursts (GRBs) are some of the most extreme events in the Universe. As well as providing a natural laboratory for investigating fundamental physical processes, they might trace the cosmic star formation rate up to extreme redshifts and probe the composition of the intergalactic medium over most of the Universe's history. Radio observations of GRBs play a key part in determining their physical properties, but currently they are largely limited to follow-up observations of $\\gamma$-ray-detected objects. The SKA will significantly increase our ability to study GRB afterglows, following up several hundred objects in the high frequency bands already in the "early science" implementation of the telescope. SKA1-MID Bands 4 (4 GHz) and 5 (9.2 GHz) will be particularly suited to the detection of these transient phenomena. The SKA will trace the peak of the emission, sampling the thick-to-thin transition of the evolving spectrum, and follow-up the afterglow down to the time the ejecta slow down to non-relativistic speeds. The full SKA will be able to observe the afterglows across the non-relativistic transition, for ~25% of the whole GRB population. This will allow us to get a significant insight into the true energy budget of GRBs, probe their surrounding density profile, and the shock microphysics. The SKA will also be able to routinely detect the elusive "orphan afterglow" emission, from the population of GRBs whose jets are not pointed towards the Earth. We expect that a deep all-sky survey such as SKA1-SUR will see around 300 orphan afterglows every week. We predict these detection to be >1000 when the full SKA telescope will be operational.

  8. Near-infrared instrumentation for rapid-response astronomy

    NASA Astrophysics Data System (ADS)

    Capone, John Isaac

    gamma-ray bursts (GRBs) are the Universe's most luminous transient events. Since the discovery of GRBs was announced in 1973, efforts have been ongoing to obtain data over a broader range of the electromagnetic spectrum at the earliest possible times following the initial detection. The discovery of the theorized "afterglow'' emission in radio through X-ray bands in the late 1990s confirmed the cosmological nature of these events. At present, GRB afterglows are among the best probes of the early Universe (z ≥ 9). In addition to informing theories about GRBs themselves, observations of afterglows probe the circum-burst medium (CBM), properties of the host galaxies and the progress of cosmic reionization. To explore the early-time variability of afterglows, I have developed a generalized analysis framework which models near-infrared (NIR), optical, ultra-violet (UV) and X-ray light curves without assuming an underlying model. These fits are then used to construct the spectral energy distribution (SED) of afterglows at arbitrary times within the observed window. Physical models are then used to explore the evolution of the SED parameter space with time. I demonstrate that this framework produces evidence of the photodestruction of dust in the CBM of GRB 120119A, similar to the findings from a previous study of this afterglow. The framework is additionally applied to the afterglows of GRB 140419A and GRB 080607. In these cases the evolution of the SEDs appears consistent with the standard fireball model. Having introduced the scientific motivations for early-time observations, I introduce the Rapid Infrared Imager-Spectrometer (RIMAS). Once commissioned on the 4.3 meter Discovery Channel Telescope (DCT), RIMAS will be used to study the afterglows of GRBs through photometric and spectroscopic observations beginning within minutes of the initial burst. The instrument will operate in the NIR, from 0.97 microm to 2.37 microm, permitting the detection of very high

  9. A Correlation Between Intrinsic Brightness and Average Decay Rate of Swift UVOT GRB Optical/UV Light Curves

    NASA Technical Reports Server (NTRS)

    Oates, S. R.; Page, M. J.; De Pasquale, M.; Schady, P.; Breeveld, A. A.; Holland, S. T.; Kuin, N. P. M.; Marshall, F. E.

    2012-01-01

    We examine a sample of 48 Swift/UVOT long Gamma-ray Burst light curves and find a correlation between the logarithmic luminosity at 200s and average decay rate determined from 200s onwards, with a Spearman rank coefficient of -0.58 at a significance of 99.998% (4.2 sigma ). We discuss the causes of the log L200s - alpha (greater than) 200s correlation, finding it to be an intrinsic property of long GRBs, and not resulting from the selection criteria. We find two ways to produce the correlation. One possibility is that there is some property of the central engine, outflow or external medium that affects the rate of energy release so that the bright afterglows release their energy more quickly and decay faster than the fainter afterglows. Alternatively, the correlation may be produced by variation of the observers viewing angle, with observers at large viewing angles observing fainter and slower decaying light curves.

  10. KSC-04PD-2108

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. Technician Grace Miller-Swales (left) does touch-up work on the Swift spacecraft in Hangar AE at Cape Canaveral Air Force Station. John DiBatilito, with Quality Assurance Services, is at right. Swift is wrapped with blankets to provide thermal stability during the mission. Swift is a first-of-its-kind multi-wavelength observatory dedicated to the study of gamma-ray burst (GRB) science. Its three instruments will work together to observe GRBs and afterglows in the gamma- ray, X-ray, ultraviolet and optical wavebands. The most comprehensive study of GRB afterglows to date, Swift is expected to observe more than 200 gamma-ray bursts during its 2-year mission.

  11. KSC-04PD-2110

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. Technician Grace Miller-Swales (left) does touch-up work on the Swift spacecraft in Hangar AE at Cape Canaveral Air Force Station. John DiBatilito is at right. Swift is wrapped with blankets to provide thermal stability during the mission. Swift is a first-of-its-kind multi-wavelength observatory dedicated to the study of gamma-ray burst (GRB) science. Its three instruments will work together to observe GRBs and afterglows in the gamma-ray, X-ray, ultraviolet and optical wavebands. The most comprehensive study of GRB afterglows to date, Swift is expected to observe more than 200 gamma-ray bursts during its 2-year mission.

  12. KSC-04PD-2109

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. Technician Grace Miller-Swales (left) does touch-up work on the Swift spacecraft in Hangar AE at Cape Canaveral Air Force Station. John Batilito, with Quality Assurance Services, is at right. Swift is wrapped with blankets to provide thermal stability during the mission. Swift is a first-of-its-kind multi-wavelength observatory dedicated to the study of gamma-ray burst (GRB) science. Its three instruments will work together to observe GRBs and afterglows in the gamma- ray, X-ray, ultraviolet and optical wavebands. The most comprehensive study of GRB afterglows to date, Swift is expected to observe more than 200 gamma-ray bursts during its 2-year mission.

  13. Constraining the mass of the photon with gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Zhang, Bo; Chai, Ya-Ting; Zou, Yuan-Chuan; Wu, Xue-Feng

    2016-09-01

    One of the cornerstones of modern physics is Einstein's special relativity, with its constant speed of light and zero photon mass assumptions. Constraint on the rest mass mγ of photons is a fundamental way to test Einstein's theory, as well as other essential electromagnetic and particle theories. Since non-zero photon mass can give rise to frequency- (or energy-) dependent dispersions, measuring the time delay of photons with different frequencies emitted from explosive astrophysical events is an important and model-independent method to put such a constraint. The cosmological gamma-ray bursts (GRBs), with short time scales, high redshifts as well as broadband prompt and afterglow emissions, provide an ideal testbed for mγ constraints. In this paper we calculate the upper limits of the photon mass with GRB early time radio afterglow observations as well as multi-band radio peaks, thus improve the results of Schaefer (1999) by nearly half an order of magnitude.

  14. MAGIC Telescope Observations of Gamma-Ray Bursts

    SciTech Connect

    Garczarczyk, M.; Becerra-Gonzalez, J.; Gaug, M.; Antonelli, A.; Carosi, A.; La Barbera, A.; Spiro, S.; Bastieri, D.; Covino, S.; Dominguez, A.; Longo, F.; Scapin, V.

    2010-10-15

    MAGIC is built to perform observations of prompt and early afterglow emission from Gamma-Ray Bursts (GRBs) above 25 GeV. The instrument is designed to have the lowest possible energy threshold among the ground based {gamma}-ray detectors and the fastest reaction time to alerts distributed over the GRB Coordinates Network (GCN). The MAGIC-I telescope observed 57 GRBs during the first six years. In no cases Very High Energy (VHE){gamma}-ray emission above the threshold energy could be detected. The telescope has undergone several major improvements in sensitivity and repositioning performance. The biggest improvement in sensitivity was achieved with the installation of the second MAGIC-II telescope. Since more than one year both telescopes are observing in stereo mode. MAGIC are the only telescopes fast and sensitive enough to extend the observational energy range of satellite detectors, while GRB prompt and early afterglow emission is still ongoing.

  15. KSC-04PD-1591

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. Inside Hangar AE at Cape Canaveral Air Force Station (CCAFS), workers secure the Swift spacecraft, wrapped in a protective cover, on a work stand. Swift is a first- of-its-kind, multi-wavelength observatory dedicated to the study of gamma-ray burst (GRB) science. Its three instruments will work together to observe GRBs and afterglows in the gamma-ray, X-ray and optical wavebands. Swift is part of NASAs medium explorer (MIDEX) program being developed by an international collaboration. It will be launched no earlier than Oct. 7 into a low-Earth orbit on a Boeing Delta 7320 rocket from pad 17-A at CCAFS. During its nominal 2-year mission, Swift is expected to observe more than 200 bursts, which will represent the most comprehensive study of GRB afterglow to date.

  16. Enhanced Photocatalytic Performance of Luminescent g-C3N4 Photocatalyst in Darkroom

    NASA Astrophysics Data System (ADS)

    Li, Huihui; Yin, Shu; Sato, Tsugio; Wang, Yuhua

    2016-02-01

    Graphitic-C3N4(g-C3N4), a low-cost visible-light-driven photocatalyst, was used for the photocatalytic oxidation of aqueous methylene blue (MB) in the dark with Sr4Al14O25:(Eu,Dy) assistance. The Sr4Al14O25:(Eu,Dy)/g-C3N4 photocatalysts were fabricated through the ultrasonic dispersion method. The commercial Sr4Al14O25:(Eu,Dy) phosphor was used as a long afterglow supplier for exciting g-C3N4 in the dark. The results demonstrated that the metal-free g-C3N4 photocatalyst could use the eye-visible long afterglow to photocatalytically decompose MB dyes in the dark. This work may expand the appealing application of g-C3N4 for the environmental cleanup.

  17. Broadband Study of GRB 091127: A Sub-Energetic Burst at Higher Redshift?

    NASA Technical Reports Server (NTRS)

    Troja, E.; Sakamoto, T.; Guidorzi, C.; Norris, J. P.; Panaitescu, A.; Kobayashi, S.; Omodei, N.; Brown, J. C.; Burrows, D. N.; Evans, P. A.; Gehrels, N.; Marshall, F. E.; Mawson, N.; Melandri,; Mundell, C. G.; Oates, S. R.; Pal'shin, V.; Preece, R. D.; Racusin, J. L.; Steele, I. A.; Tanvir, N. R.; Vasileiou, V.; Wilson-Hodge, C.

    2012-01-01

    GRB 091127 is a bright gamma-ray burst (GRB) detected by Swift at a redshift z=0.49 and associated with SN 2009nz. We present the broadband analysis of the GRB prompt and afterglow emission and study its high-energy properties in the context of the GRB/SN association. While the high luminosity of the prompt emission and standard afterglow behavior are typical of cosmological long GRBs, its low energy release (E(sub gamma),<3x10(exp 49) erg), soft spectrum and unusual spectral lag connect this GRB to the class of sub-energetic bursts. We discuss the suppression of high-energy emission in this burst, and investigate whether this behavior could be connected with the sub-energetic nature of the explosion. Subject headings: gamma-ray bursts: individual (GRB 091127)

  18. SHORT-DURATION GAMMA-RAY BURSTS FROM OFF-AXIS COLLAPSARS

    SciTech Connect

    Lazzati, Davide; Morsony, Brian J.; Begelman, Mitchell C.

    2010-07-01

    We present two-dimensional (2D) high-resolution hydrodynamic simulations of the relativistic outflows of long-duration gamma-ray burst (GRB) progenitors. We analyze the properties of the outflows at wide off-axis angles, produced by the expansion of the hot cocoon that surrounds the jet inside the progenitor star. We find that the cocoon emission at wide angles may have properties similar to those of the subclass of short-duration GRBs with persistent X-ray emission. We compute the predicted duration distribution, redshift distribution, and afterglow brightness, and we find that they are all in agreement with the observed properties of short GRBs with persistent emission. We suggest that a supernova component, the properties of the host galaxies, and late afterglow observations can be used as a crucial test to verify this model.

  19. Phosphor-in-glass for high-powered remote-type white AC-LED.

    PubMed

    Lin, Hang; Wang, Bo; Xu, Ju; Zhang, Rui; Chen, Hui; Yu, Yunlong; Wang, Yuansheng

    2014-12-10

    The high-powered alternating current (AC) light-emitting diode (LED) (AC-LED), featuring low cost, high energy utilization efficiency, and long service life, will become a new economic growth point in the field of semiconductor lighting. However, flicker of AC-LED in the AC cycles is not healthy for human eyes, and therefore need to be restrained. Herein we report an innovation of persistent "phosphor-in-glass" (PiG) for the remote-type AC-LED, whose afterglow can be efficiently activated by the blue light. It is experimentally demonstrated that the afterglow decay of PiG in the microsecond range can partly compensate the AC time gap. Moreover, the substitution of inorganic glass for organic resins or silicones as the encapsulants would bring out several technological benefits to AC-LED, such as good heat-dissipation, low glare, and excellent physical/chemical stability.

  20. Near-infrared long-persistent phosphor of Zn₃Ga ₂Ge ₂O₁₀: Cr³⁺ sintered in different atmosphere.

    PubMed

    Wu, Yiling; Li, Yang; Qin, Xixi; Chen, Ruchun; Wu, Dakun; Liu, Shijian; Qiu, Jianrong

    2015-01-01

    A variety of materials sintered in different atmosphere have been well investigated, but there are few reports on the long-persistent phosphorescent materials, especially the near-infrared long-persistent phosphorescent materials sintered in various atmosphere. Changing the surrounding atmosphere is an effective method to improve the afterglow properties of the materials. In this work, we fabricate a typical kind of near-infrared long-persistent phosphorescent materials of Zn3Ga2Ge2O10: 0.5% Cr(3+) in neutral, oxidizing, and reducing atmosphere. By analyzing the XRD patterns, afterglow spectra, decay and thermo-luminescence curves, we discuss the great effects on the structure, long persistent properties and trap properties of the phosphor. This work of obtaining the Zn3Ga2Ge2O10: 0.5% Cr(3+) is of great potential in the applications in night-vision surveillance and in vivo bio-imaging.

  1. DR Experiments in the 60 years since the Bates paper

    NASA Astrophysics Data System (ADS)

    Johnsen, Rainer

    2011-07-01

    About 60 years have passed since David Bates in a 1950 Physical Review Letter to the Editor first clarified the dissociative recombination mechanism (DR) of molecular ions and provided the conceptual basis for the process that plays an important role in the ionospheres of Earth and other planets, the interstellar medium, and electrical discharges. His visionary (and characteristically "terse") thumbnail sketch of the DR mechanism only hinted at the subtleties that have kept atomic theorists and experimentalists busy for many years. In my talk, I will focus on experiments on N2+ recombination, beginning with plasma afterglows, and then move on to the "after"-afterglow period that is now dominated by the powerful storage-ring methods.

  2. Gamma Ray Bursts - Observations

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Cannizzo, J. K.

    2010-01-01

    We are in an exciting period of discovery for gamma-ray bursts. The Swift observatory is detecting 100 bursts per year, providing arcsecond localizations and sensitive observations of the prompt and afterglow emission. The Fermi observatory is observing 250 bursts per year with its medium-energy GRB instrument and about 10 bursts per year with its high-energy LAT instrument. In addition, rapid-response telescopes on the ground are providing new capabilities to study optical emission during the prompt phase and spectral signatures of the host galaxies. The combined data set is enabling great advances in our understanding of GRBs including afterglow physics, short burst origin, and high energy emission.

  3. Experimental study and modeling of the deuterium releasing quantity in a pulsed vacuum arc discharge with a metal deuteride cathode

    NASA Astrophysics Data System (ADS)

    Liu, Fei-Xiang; Long, Ji-Dong; Zheng, Le; Dong, Pan; Li, Chen; Chen, Wei

    2017-04-01

    The pulsed vacuum arc discharge using a metal deuteride cathode is widely applied as a deuterium ion source, where the upper limit of the deuterium ion yield is largely determined by the deuterium releasing quantity (DRQ) from the cathode. This work aims to measure the DRQ at various discharge conditions, and meanwhile develop a simple thermoelectric model to evaluate the deuterium liberation from different sources, such as the crater vicinity during the arc power-on phase and the hot crater in the afterglow. The calculated DRQ are in accordance with the experimental results obtained by measuring the D2 pressure evolution in the early afterglow using a quadrupole mass spectrometer. Furthermore, the model reveals that at low arc current (<10 A), the DRQ orginates dominantly from the crater vicinity, leading to a low conversion efficiency of the released deuterium to ions and a high D:Ti elemental ratio in the released cathode vapor.

  4. Reaction of anthracene with atomic ions of interstellar interest. A FALP measurement at room temperature

    NASA Astrophysics Data System (ADS)

    Canosa, A.; Laubé, S.; Rebrion, C.; Pasquerault, D.; Gomet, J. C.; Rowe, B. R.

    1995-11-01

    We present the results obtained on studying the reaction of anthracene with some atomic ions of interstellar interest (He + and C +) and with Ar +. Rate coefficients have been measured at room temperature (293 K) in afterglow experiments using flowing afterglow Langmuir probe-mass spectrometer apparatus. Reactions proceed with rate coefficients of respectively 5.2 × 10 -9, 3 × 10 -9, 1 × 10 -9 cm 3 s -1 for He +, C + and Ar +. The results were obtained with an uncertainty of about 30% and were found to be close to the Langevin rate. The nature of the products has also been investigated. More particularly, the evidence for carbon accretion and for the production of doubly charged species is discussed.

  5. Dissociative recombination of protonated dimer ions H+·(HCOH)2 and H+·(CH3COH)2 with electrons at near thermal energies

    NASA Astrophysics Data System (ADS)

    Glosík, J.; Plasil, R.; Zakouril, P.; Poterya, V.

    2001-07-01

    Formation of the protonated formaldehyde and acetaldehyde dimer ions, H+·(HCOH)2 and H+·(CH3COH)2, respectively, and their subsequent dissociative recombination with electrons was studied in a high-pressure flowing afterglow (HPFA) using the axially movable Langmuir probe. The obtained recombination rate coefficients are (3.3±1)×10-6 cm3 s-1 for H+·(HCOH)2 and (1.4±0.5)×10-6 cm3 s-1 for H+·(CH3COH)2, at 450 and 500 K, respectively. The evolution of the electron energy distribution function and the electron temperature in the recombination-dominated flowing afterglow plasma were also measured.

  6. Recombination of HCO+ and DCO+ ions with electrons

    NASA Astrophysics Data System (ADS)

    Korolov, I.; Plasil, R.; Kotrik, T.; Dohnal, P.; Glosik, J.

    2009-02-01

    Recombination of HCO+ and DCO+ ions with electrons was studied in afterglow plasma. The flowing afterglow with Langmuir probe (FALP) apparatus was used to measure the recombination rate coefficients and their temperature dependencies in the range 150-270 K. To obtain a recombination rate coefficient for a particular ion, the dependencies on partial pressures of gases used in the ion formation were measured. The variations of [alpha]HCO+(T) and [alpha]DCO+(T) seem to obey the power law: [alpha]HCO+(T) = (2.0 ± 0.6) × 10-7 (T/300)-1.3 cm3 s-1 and [alpha]DCO+(T) = (1.7 ± 0.5) × 10-7 (T/300)-1.1 cm3 s-1 over the studied temperature range.

  7. Dissociative electron attachment to C2F5 radicals.

    PubMed

    Haughey, Sean A; Field, Thomas A; Langer, Judith; Shuman, Nicholas S; Miller, Thomas M; Friedman, Jeffrey F; Viggiano, A A

    2012-08-07

    Dissociative electron attachment to the reactive C(2)F(5) molecular radical has been investigated with two complimentary experimental methods; a single collision beam experiment and a new flowing afterglow Langmuir probe technique. The beam results show that F(-) is formed close to zero electron energy in dissociative electron attachment to C(2)F(5). The afterglow measurements also show that F(-) is formed in collisions between electrons and C(2)F(5) molecules with rate constants of 3.7 × 10(-9) cm(3) s(-1) to 4.7 × 10(-9) cm(3) s(-1) at temperatures of 300-600 K. The rate constant increases slowly with increasing temperature, but the rise observed is smaller than the experimental uncertainty of 35%.

  8. Dissociative electron attachment to C{sub 2}F{sub 5} radicals

    SciTech Connect

    Haughey, Sean A.; Field, Thomas A.; Langer, Judith; Shuman, Nicholas S.; Miller, Thomas M.; Friedman, Jeffrey F.; Viggiano, A. A.

    2012-08-07

    Dissociative electron attachment to the reactive C{sub 2}F{sub 5} molecular radical has been investigated with two complimentary experimental methods; a single collision beam experiment and a new flowing afterglow Langmuir probe technique. The beam results show that F{sup -} is formed close to zero electron energy in dissociative electron attachment to C{sub 2}F{sub 5}. The afterglow measurements also show that F{sup -} is formed in collisions between electrons and C{sub 2}F{sub 5} molecules with rate constants of 3.7 Multiplication-Sign 10{sup -9} cm{sup 3} s{sup -1} to 4.7 Multiplication-Sign 10{sup -9} cm{sup 3} s{sup -1} at temperatures of 300-600 K. The rate constant increases slowly with increasing temperature, but the rise observed is smaller than the experimental uncertainty of 35%.

  9. Dissociative electron attachment to C2F5 radicals

    NASA Astrophysics Data System (ADS)

    Haughey, Sean A.; Field, Thomas A.; Langer, Judith; Shuman, Nicholas S.; Miller, Thomas M.; Friedman, Jeffrey F.; Viggiano, A. A.

    2012-08-01

    Dissociative electron attachment to the reactive C2F5 molecular radical has been investigated with two complimentary experimental methods; a single collision beam experiment and a new flowing afterglow Langmuir probe technique. The beam results show that F- is formed close to zero electron energy in dissociative electron attachment to C2F5. The afterglow measurements also show that F- is formed in collisions between electrons and C2F5 molecules with rate constants of 3.7 × 10-9 cm3 s-1 to 4.7 × 10-9 cm3 s-1 at temperatures of 300-600 K. The rate constant increases slowly with increasing temperature, but the rise observed is smaller than the experimental uncertainty of 35%.

  10. Measurements of recombination of electrons with HCO(plus) ions

    NASA Technical Reports Server (NTRS)

    Leu, M. T.; Biondi, M. A.; Johnsen, R.

    1973-01-01

    Recombination coefficients of electrons with HCO(+) ions were determined with a microwave afterglow/mass spectrometer apparatus. Afterglow measurements of electron density decays in neon-hydrogen-carbon monoxide mixtures are correlated with the decay of mass-identified ion currents to the wall of the microwave cavity. At the appropriate partial pressures of hydrogen and carbon monoxide in the mixture, the ion HCO(+) dominates the ion composition and its wall current approximately tracks the electron density decay curve. From recombination controlled electron density decay curves, the values alpha (HCO(+)) = (3.3 + or - 0.5) and (2.0 + or - 0.3) 0.0000001 cu cm/sec are obtained at 205 and 300 K, respectively. The implications of these results for models of polyatomic molecule formation in dense interstellar clouds are briefly discussed.

  11. Fundamental studies of reactive intermediates in homogeneous catalysis. Final technical report

    SciTech Connect

    1998-09-01

    The chief aims during the contract period were to design, construct and implement a new flowing afterglow-guided ion beam instrument for use in determining thermochemical properties of organometallic species pertinent to homogeneous catalysis, and to develop an electrospray ionization (ESI) source for the flowing afterglow-triple quadrupole apparatus for use in real-time analysis of reactive intermediates in catalytically active solutions. Both goals were achieved. In parallel with development of the guided ion beam and electrospray ionization experiments, the author used existing equipment to work on some of the problems outlined in the previous proposal, and to open up new research areas. A summary of research activities and publications acknowledging DOE support follows.

  12. Implementation and Operation of a Robotic Telescope on Skynet

    NASA Astrophysics Data System (ADS)

    Smith, Adam B.; Caton, Daniel B.; Hawkins, R. Lee

    2016-05-01

    We describe the implementation of a remotely operated telescope on the Skynet Robotic Telescope Network, a system developed and run by the University of North Carolina-Chapel Hill. Our telescope, operated by Appalachian State University at its Dark Sky Observatory, runs robotically on this queue-scheduled system, automatically taking calibration images and acquiring program images, and responding to Internet commands to image the afterglow of accessible Gamma-Ray Burst events. We describe the process of implementing a Skynet-run telescope from our client-side view, and offer advice for others who might consider putting telescopes on Skynet. The implementation has proven very successful, obtaining over a hundred thousand images over the past six years, of various targets for research and educational purposes, and has responded to several GRB observation requests with several afterglow detections.

  13. Electronic structure and luminescence properties of Ca2Ge7O16:Dy3+

    NASA Astrophysics Data System (ADS)

    Leonidov, I. I.; Ishchenko, A. V.; Konstantinova, E. I.; Petrov, V. P.; Chernyshev, V. A.; Nikiforov, A. E.

    2016-12-01

    The present report represents an overview of the results of a combined experimental-computational study of electronic structure, thermoluminescence (TL) and afterglow properties of Ca2Ge7O16:Dy3+ synthesized for the first time. Afterglow curves of Ca2Ge7O16:Dy3+ at 575 nm showing persistent luminescence have been described in Becquerel law. The TL measurements reveal at least one TL band at 326 K and two luminescence bands at 475 and 535 nm. Persistent luminescence in Ca2Ge7O16:Dy3+ originates from relatively shallow charge traps with high probability of charge carriers recapture. The model of energy processes, configurations of traps and luminescence centers has been proposed with the aid of ab initio calculations performed using the LCAO approximation and several hybrid functionals.

  14. KSC-04PD-1589

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. Inside Hangar AE at Cape Canaveral Air Force Station (CCAFS), an overhead crane raises the Swift spacecraft, wrapped in a protective cover, to vertical before being placed on a work stand. Swift is a first-of-its-kind, multi-wavelength observatory dedicated to the study of gamma-ray burst (GRB) science. Its three instruments will work together to observe GRBs and afterglows in the gamma-ray, X-ray and optical wavebands. Swift is part of NASAs medium explorer (MIDEX) program being developed by an international collaboration. It will be launched no earlier than Oct. 7 into a low-Earth orbit on a Boeing Delta 7320 rocket from pad 17-A at CCAFS. During its nominal 2-year mission, Swift is expected to observe more than 200 bursts, which will represent the most comprehensive study of GRB afterglow to date.

  15. Enhanced Photocatalytic Performance of Luminescent g-C3N4 Photocatalyst in Darkroom.

    PubMed

    Li, Huihui; Yin, Shu; Sato, Tsugio; Wang, Yuhua

    2016-12-01

    Graphitic-C3N4(g-C3N4), a low-cost visible-light-driven photocatalyst, was used for the photocatalytic oxidation of aqueous methylene blue (MB) in the dark with Sr4Al14O25:(Eu,Dy) assistance. The Sr4Al14O25:(Eu,Dy)/g-C3N4 photocatalysts were fabricated through the ultrasonic dispersion method. The commercial Sr4Al14O25:(Eu,Dy) phosphor was used as a long afterglow supplier for exciting g-C3N4 in the dark. The results demonstrated that the metal-free g-C3N4 photocatalyst could use the eye-visible long afterglow to photocatalytically decompose MB dyes in the dark. This work may expand the appealing application of g-C3N4 for the environmental cleanup.

  16. KSC-04PD-1587

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. Inside Hangar AE at Cape Canaveral Air Force Station (CCAFS), workers observe the canister being lifted from the Swift spacecraft, which is enclosed in a protective cover. Swift is a first-of-its-kind, multi-wavelength observatory dedicated to the study of gamma-ray burst (GRB) science. Its three instruments will work together to observe GRBs and afterglows in the gamma-ray, X-ray and optical wavebands. Swift is part of NASAs medium explorer (MIDEX) program being developed by an international collaboration. It will be launched no earlier than Oct. 7 into a low-Earth orbit on a Boeing Delta 7320 rocket from pad 17-A at CCAFS. During its nominal 2-year mission, Swift is expected to observe more than 200 bursts, which will represent the most comprehensive study of GRB afterglow to date.

  17. Photometric Observations of Supernova 2013cq Associated with GRB 130427A

    NASA Astrophysics Data System (ADS)

    Becerra, R. L.; Watson, A. M.; Lee, W. H.; Fraija, N.; Butler, N. R.; Bloom, J. S.; Capone, J. I.; Cucchiara, A.; de Diego, J. A.; Fox, O. D.; Gehrels, N.; Georgiev, L. N.; González, J. J.; Kutyrev, A. S.; Littlejohns, O. M.; Prochaska, J. X.; Ramirez-Ruiz, E.; Richer, M. G.; Román-Zúñiga, C. G.; Toy, V. L.; Troja, E.

    2017-03-01

    We observed the afterglow of GRB 130427A with the Reionization and Transients Infrared Camera (RATIR) instrument on the 1.5 m Harold L. Johnson telescope of the Observatorio Astronómico Nacional in Sierra San Pedro Mártir. Our homogenous griZY JH photometry extends from the night of the burst to three years later. We fit a model for the afterglow. There is a significant positive residual that matches the behavior of SN 1998bw in the griZ filters; we suggest that this is a photometric signature of the supernova SN 2013cq associated with the Gamma-ray burst. The peak absolute magnitude of the supernova is {M}r=-18.43+/- 0.11.

  18. Kinetic Processes in High Pressure Gases: Excited State Collisions.

    DTIC Science & Technology

    1980-12-01

    Missouri-Rolla Rolla, MO 65401 Technical Report to the Office of Naval Research Grant No. N00014-75-C-0477 for the period December 1979 - December 1980...DESCRIPTION The purpose of the research program is to investigate energy exchange and energy loss mechanisms in discharge plasmas and their afterglows...pressure of 10-6 Torr. Sodium was titrated into a reservoir attached to the reaction cell. Research grade argon was admitted to the desired pressure

  19. Method for producing metallic nanoparticles

    DOEpatents

    Phillips, Jonathan; Perry, William L.; Kroenke, William J.

    2004-02-10

    Method for producing metallic nanoparticles. The method includes generating an aerosol of solid metallic microparticles, generating non-oxidizing plasma with a plasma hot zone at a temperature sufficiently high to vaporize the microparticles into metal vapor, and directing the aerosol into the hot zone of the plasma. The microparticles vaporize in the hot zone to metal vapor. The metal vapor is directed away from the hot zone and to the plasma afterglow where it cools and condenses to form solid metallic nanoparticles.

  20. Method for producing metallic microparticles

    DOEpatents

    Phillips, Jonathan; Perry, William L.; Kroenke, William J.

    2004-06-29

    Method for producing metallic particles. The method converts metallic nanoparticles into larger, spherical metallic particles. An aerosol of solid metallic nanoparticles and a non-oxidizing plasma having a portion sufficiently hot to melt the nanoparticles are generated. The aerosol is directed into the plasma where the metallic nanoparticles melt, collide, join, and spheroidize. The molten spherical metallic particles are directed away from the plasma and enter the afterglow where they cool and solidify.

  1. The mobility and diffusion of ions in gases

    NASA Technical Reports Server (NTRS)

    Mcdaniel, E. W.; Mason, E. A.

    1973-01-01

    Experimental and theoretical aspects of the mobility and diffusion of ions in gases are studied in detail. Some of the subjects discussed include ion-ion interaction, boundary condition and ion and electron behavior. Also discussed in separate chapters are the problems of the diffusion coefficients and the afterglow techniques. Finally, a special chapter studies the kinetic theory of diffusion and mobility, stressing the low-, medium- and high-field theory.

  2. The Swift Gamma-ray Burst Explorer: Early views into Black-hole Creation

    NASA Technical Reports Server (NTRS)

    Hill, Joe

    2006-01-01

    Swift has exceeded every pre-launch predicted advance in GRB science. It has discovered the farthest GRB ever seen and identified new GRBs at a rate of 100/year. It has also explored a brand new time interval in GRB light curves by revealing unpredicted phenomena of GRB flares and rapid x-ray afterglow declines. Swift has conducted 20,00o successful slews to sources and is predicted to stay in orbit until 2022.

  3. First Detection of a Foreground Damped Ly-Alpha Absorber Along a GRB Line of Sight?

    NASA Technical Reports Server (NTRS)

    Vreeswijk, P. M.; Fruchter, A. S.; Pian, E.; Rol, E.; Wijers, R. A. M. J.; Kouveliotou, C.; Kaper, L.; Palazzi, E.; Masetti, N.; Frontera, F.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    We present a VLT spectrum of the optical afterglow of GRB 991216, taken 1.5 days after the burst, and HST (Hubble Space Telescope) imaging of the host galaxy, obtained four months later. The spectrum contains three metal absorption-line systems with redshifts z = 1.024, z = 0.803, and z = 0.771, where the highest redshift most likely reflects the distance to the host galaxy. For the z = 1.024 and z = 0.803 systems we tentatively detect MgI which suggests a dense environment at these redshifts. This and the strength of the z = 0.803 Fe lines indicate that this system very likely is a damped Ly-alpha absorber (DLA), which would be the first foreground DLA to be detected along a GRB afterglow sight line. The HST images are consistent with these findings: they show two blobs of light, one underneath the projected OT position, the presumed host galaxy, and the other 0.6" away, which is probably responsible for the absorption lines at z = 0.803. The lowest redshift system can be explained by either one of the two galaxies that are located roughly 2" away from the transient. Including these newly found systems, the total number of DLAS and Lyman limit systems along GRB afterglow sight lines is consistent with the number expected from QSO (quasi-stellar object) absorption line studies. We expect early spectroscopy of GRB afterglows to significantly increase the number of detected foreground absorption systems, and we discuss some advantages over QSO lines of sight.

  4. GRB 090417B and its Host Galaxy: A Step Towards an Understanding of Optically-Dark Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Holland, Stephen T.; Sbarufatti, Boris; Shen, Rongfeng; Schady, Patricia; Cummings, Jay R.; Fonseca, Emmanuel; Fynbo, Johan P. U.; Jakobsson, Pall; Leitet, Elisabet; Linne, Staffan; Roming, Peter W.A.; Still, Martin; Zhang, Bing

    2009-01-01

    GRB 090417B was an unusually long burst with a T(sub 90) duration of at least 2130 s and a multi-peaked light curve at energies of 15-150 keV. It was optically dark and has been convincingly associated with a bright star-forming galaxy at a redshift of 0.345 that is broadly similar to the Milky Way. This is one of the few cases where a host galaxy has been clearly identified for a dark gamma-ray burst and thus an ideal candidate for studying the origin of dark bursts. We find that the dark nature of GRB 090417B can not be explained by high redshift, incomplete observations, or unusual physics in the production of the afterglow. The Swift/XRT X-ray data are consistent with the afterglow being obscured by a dense, localized sheet of dust approximately 30-80 pc from the burst along the line of sight. Assuming the standard relativistic fireball model for the afterglow we find that the optical flux is at least 2.5 mag fainter than predicted by the X -ray flux. We are able to explain the lack of an optical afterglow, and the evolution of the X -ray spectrum, by assuming that there is a sheet of dust along the line of sight approximately 30-80 pc from the progenitor. Our results suggest that this dust sheet imparts an extinction of A(sub v)> or = 12 mag, which is sufficient to explain the missing optical flux. GRB 090417B is an example of a gamma-ray burst that is dark due to the localized dust structure in its host galaxy.

  5. Late time observations of candidate high-z GRBs

    NASA Astrophysics Data System (ADS)

    Burlon, Davide; Gaensler, Bryan; Murphy, Tara; Hancock, Paul; Ghirlanda, Giancarlo; Salvaterra, Ruben; Ghisellini, Gabriele; Tagliaferri, Gianpiero

    2014-04-01

    This is a discovery (NAPA) proposal to detect the late time radio afterglow of candidates high redshift gamma ray bursts (GRBs). Our selection criteria (no redshift information at the time of the request, type of trigger, high-energy flux and duration) are based on information immediately available through the Swift/BAT telescope and ground based telescopes. Radio observations play a crucial role in determining the energetics of the GRB explosion, and will therefore directly point towards exceptional progenitors.

  6. GRB 070724B: the first Gamma Ray Burst localized by SuperAGILE

    SciTech Connect

    Del Monte, E.; Costa, E.; Donnarumma, I.; Feroci, M.; Lapshov, I.; Lazzarotto, F.; Soffitta, P.; Argan, A.; Pucella, G.; Trois, A.; Vittorini, V.; Evangelista, Y.; Rapisarda, M.; Barbiellini, G.; Longo, F.; Basset, M.; Foggetta, L.; Vallazza, E.; Bulgarelli, A.; Di Cocco, G.

    2008-05-22

    GRB070724B is the first Gamma Ray Burst localized by the SuperAGILE instrument aboard the AGILE space mission. The SuperAGILE localization has been confirmed after the after-glow observation by the XRT aboard the Swift satellite. No significant gamma ray emission above 50 MeV has been detected for this GRB. In this paper we describe the SuperAGILE capabilities in detecting Gamma Ray Burst and the AGILE observation of GRB 070724B.

  7. Recombination of cluster ions

    NASA Technical Reports Server (NTRS)

    Johnsen, Rainer

    1993-01-01

    Some of our recent work on molecular band emissions from recombination of molecular dimer ions (N4(+) and CO(+) CO) is discussed. Much of the experimental work was done by Y. S. Cao; the results on N4(+) recombination have been published. A brief progress report is given on our ongoing measurements of neutral products of recombination using the flowing-afterglow Langmuir-probe technique in conjunction with laser-induced fluorescence.

  8. NASA EM Followup of LIGO-Virgo Candidate Events

    NASA Technical Reports Server (NTRS)

    Blackburn, Lindy L.

    2011-01-01

    We present a strategy for a follow-up of LIGO-Virgo candidate events using offline survey data from several NASA high-energy photon instruments aboard RXTE, Swift, and Fermi. Time and sky-location information provided by the GW trigger allows for a targeted search for prompt and afterglow EM signals. In doing so, we expect to be sensitive to signals which are too weak to be publicly reported as astrophysical EM events.

  9. A Search for Early Optical Emission at Gamma-Ray Burst Locations by the Solar Mass Ejection Imager (SMEI)

    NASA Technical Reports Server (NTRS)

    Band, David L.; Buffington, Andrew; Jackson, Bernard V.; Hick, P. Paul; Smith, Aaron C.

    2005-01-01

    The Solar Mass Ejection Imager (SMEI) views nearly every point on the sky once every 102 minutes and can detect point sources as faint as R approx. 10th magnitude. Therefore, SMEI can detect or provide upper limits for the optical afterglow from gamma-ray bursts in the tens of minutes after the burst when different shocked regions may emit optically. Here we provide upper limits for 58 bursts between 2003 February and 2005 April.

  10. The astronomers. Companion book to the PBS television series.

    NASA Astrophysics Data System (ADS)

    Goldsmith, D.

    Contents: 1. Under the dome of heaven. 2. The dark matter. 3. We are all astronomers. 4. Mapping the universe. 5. The afterglow of creation. 6. Why stars shine. 7. Stars from birth to old age. 8. The stellar explosions that made us. 9. Quasars and peculiar galaxies. 10. The beast in the middle. 11. Exploring the neighborhood. 12. How many worlds in the Milky Way? 13. The wave of the future? 14. Astronomy for the twenty-first century.

  11. Temperature Dependences for the Reactions of Ar+, O2+, and C7H7+ with Toluene and Ethylbenzene

    DTIC Science & Technology

    2013-07-01

    containing C7H7+. Products with 4, 5, 6, and 7 carbonswere found. The largest non-C7H7+ cation is C5H6+ at 3–4%. For reactions with known thermochemistry ...154201. 15] N.S. Shuman, T.M. Miller, A.A. Viggiano, J. Troe, Teaching an old dog new tricks: using the flowing afterglow to measure kinetics of electron

  12. Preliminary results from the TAROT experiment

    NASA Astrophysics Data System (ADS)

    Boër, M.; Atteia, J.-L.; Bringer, M.; Chaty, S.; Klotz, A.; Morand, F.; Pedersen, H.; Pollas, C.; Toublanc, D.

    2000-09-01

    TAROT-1 has been operating routinely since July 1999. During that time 6 alerts have been observed in good weather conditions, leading to limits in magnitude of about R=14 to 17 for the early afterglow of the gamma-ray burst sources. Future prospects include the replacement of the present camera by a more sensitive one, a larger field of view, and an improved readout time. .

  13. Synchrotron self-inverse Compton radiation from reverse shock on GRB 120326A

    SciTech Connect

    Urata, Yuji; Huang, Kuiyun; Takahashi, Satoko; Im, Myungshin; Kim, Jae-Woo; Jang, Minsung; Yamaoka, Kazutaka; Tashiro, Makoto; Pak, Soojong

    2014-07-10

    We present multi-wavelength observations of a typical long duration GRB 120326A at z = 1.798, including rapid observations using a Submillimeter Array (SMA) and a comprehensive monitoring in the X-ray and optical. The SMA observation provided the fastest detection to date among seven submillimeter afterglows at 230 GHz. The prompt spectral analysis, using Swift and Suzaku, yielded a spectral peak energy of E{sub peak}{sup src}=107.8{sub −15.3}{sup +15.3} keV and an equivalent isotropic energy of E{sub iso} as 3.18{sub −0.32}{sup +0.40}×10{sup 52} erg. The temporal evolution and spectral properties in the optical were consistent with the standard forward shock synchrotron with jet collimation (6.°69 ± 0.°16). The forward shock modeling, using a two-dimensional relativistic hydrodynamic jet simulation, was also determined by the reasonable burst explosion and the synchrotron radiation parameters for the optical afterglow. The X-ray light curve showed no apparent jet break and the temporal decay index relation between the X-ray and optical (αo – α{sub X} = –1.45 ± 0.10) indicated different radiation processes in each of them. Introducing synchrotron self-inverse Compton radiation from reverse shock is a possible solution, and the detection and slow decay of the afterglow in submillimeter supports that this is a plausible idea. The observed temporal evolution and spectral properties, as well as forward shock modeling parameters, enabled us to determine reasonable functions to describe the afterglow properties. Because half of the events share similar properties in the X-ray and optical as the current event, GRB 120326A will be a benchmark with further rapid follow-ups, using submillimeter instruments such as an SMA and the Atacama Large Millimeter/submillimeter Array.

  14. THE OPTICALLY UNBIASED GRB HOST (TOUGH) SURVEY. V. VLT/X-SHOOTER EMISSION-LINE REDSHIFTS FOR SWIFT GRBs AT z {approx} 2

    SciTech Connect

    Kruehler, Thomas; Malesani, Daniele; Milvang-Jensen, Bo; Fynbo, Johan P. U.; Hjorth, Jens; Sparre, Martin; Watson, Darach J.; Jakobsson, Pall; Levan, Andrew J.; Tanvir, Nial R.

    2012-10-10

    We present simultaneous optical and near-infrared (NIR) spectroscopy of 19 Swift {gamma}-ray burst (GRB) host galaxies observed with the VLT/X-shooter with the aim of measuring their redshifts. Galaxies were selected from The Optically Unbiased GRB Host (TOUGH) survey (15 of the 19 galaxies) or because they hosted GRBs without a bright optical afterglow. Here we provide emission-line redshifts for 13 of the observed galaxies with brightnesses between F606W > 27 mag and R = 22.9 mag (median R-tilde =24.6 mag). The median redshift is z-tilde =2.1 for all hosts and z-tilde =2.3 for the TOUGH hosts. Our new data significantly improve the redshift completeness of the TOUGH survey, which now stands at 77% (53 out of 69 GRBs). They furthermore provide accurate redshifts for nine prototype dark GRBs (e.g., GRB 071021 at z = 2.452 and GRB 080207 at z = 2.086), which are exemplary of GRBs where redshifts are challenging to obtain via afterglow spectroscopy. This establishes X-shooter spectroscopy as an efficient tool for redshift determination of faint, star-forming, high-redshift galaxies such as GRB hosts. It is hence a further step toward removing the bias in GRB samples that is caused by optically dark events, and provides the basis for a better understanding of the conditions in which GRBs form. The distribution of column densities as measured from X-ray data (N{sub H,X}), for example, is closely related to the darkness of the afterglow and skewed toward low N{sub H,X} values in samples that are dominated by bursts with bright optical afterglows.

  15. GRB 081007 AND GRB 090424: THE SURROUNDING MEDIUM, OUTFLOWS, AND SUPERNOVAE

    SciTech Connect

    Jin Zhiping; Covino, Stefano; Fugazza, Dino; Melandri, Andrea; Campana, Sergio; D'Avanzo, Paolo; Della Valle, Massimo; Ferrero, Patrizia; Malesani, Daniele; Fynbo, Johan P. U.; Hjorth, Jens; Pian, Elena; Salvaterra, Ruben; Bersier, David; Cano, Zach; Castro-Tirado, Alberto J.; Gorosabel, Javier; Guidorzi, Cristiano; Haislip, Joshua B.; and others

    2013-09-10

    We discuss the results of the analysis of multi-wavelength data for the afterglows of GRB 081007 and GRB 090424, two bursts detected by Swift. One of them, GRB 081007, also shows a spectroscopically confirmed supernova, SN 2008hw, which resembles SN 1998bw in its absorption features, while the maximum magnitude may be fainter, up to 0.7 mag, than observed in SN 1998bw. Bright optical flashes have been detected in both events, which allows us to derive solid constraints on the circumburst-matter density profile. This is particularly interesting in the case of GRB 081007, whose afterglow is found to be propagating into a constant-density medium, yielding yet another example of a gamma-ray burst (GRB) clearly associated with a massive-star progenitor which did not sculpt the surroundings with its stellar wind. There is no supernova component detected in the afterglow of GRB 090424, likely due to the brightness of the host galaxy, comparable to the Milky Way. We show that the afterglow data are consistent with the presence of both forward- and reverse-shock emission powered by relativistic outflows expanding into the interstellar medium. The absence of optical peaks due to the forward shock strongly suggests that the reverse-shock regions should be mildly magnetized. The initial Lorentz factor of outflow of GRB 081007 is estimated to be {Gamma} {approx} 200, while for GRB 090424 a lower limit of {Gamma} > 170 is derived. We also discuss the prompt emission of GRB 081007, which consists of just a single pulse. We argue that neither the external forward-shock model nor the shock-breakout model can account for the prompt emission data and suggest that the single-pulse-like prompt emission may be due to magnetic energy dissipation of a Poynting-flux-dominated outflow or to a dissipative photosphere.

  16. NO2 Photodissociation Dynamics

    DTIC Science & Technology

    1989-09-01

    Koons discussed electric field and plasma wave measurements on satellite and rocket flights. Many of these studies were made with a Langmuir probe , and...is an effective probe for studying predissociative effects and identifying exit channels for Rydberg state deconposition. (4) the radiative lifetimes...being similar to the so-called air afterglow , although shifted towards longer wavelengths. With the implication that nitrogen and oxygen hitting the

  17. Collisonless Dynamics of the Magnetosphere

    DTIC Science & Technology

    1993-08-01

    the ion- ’ ’Ant I ol 3 saturation current to a Langmuir probe , the hydrogen gas pressure, the forward and reflected microwave power, and the x-ray...whereas, during the afterglow , the probe signals are seen to evolve more gradually. The quasi-periodic bursts correspond to rapid radial transport of...experiment during the production of an energetic electron belt using microwave heating. (a) Langmuir probe ion saturation current, (b) hydrogen gas

  18. Thermal electron attachment to SO3

    SciTech Connect

    Miller, T.M.; Viggiano, A.A.; Arnold, S.T.; Jayne, J.T.

    1995-04-15

    The rate constant for electron attachment to SO3 is 3 + or - 1 x 10(exp-9) cu cm/s at 300 K, measured in helium gas at pressures from 53 to 160 Pa (0.4 to 1.2 torr). The sole product of attachment is SO3(-) under these conditions. The same rate constant and ionic product were obtained at 400 and 505 K. The measurements were carried out using a flowing-afterglow Langmuir-probe apparatus.

  19. Semiconductor Diamond Technology

    DTIC Science & Technology

    1991-12-31

    significantly reduce the loss rates at low pressure. \\\\Water p:ssivatinn of rtia unuls in 37 II flowing afterglow hydrogen- discharges has been used -to...These-, *servations are complemented’ by probe measurements -that provide a quantitative description of plasma properties over-an useful range of...still remains from the E discharge. The if discharges between parallel electrodes ex- III. PROBE TECHNIQUE hibit similar features- regarding ihe

  20. Thermal electron attachment to SO3

    NASA Astrophysics Data System (ADS)

    Miller, Thomas M.; Viggiano, A. A.; Arnold, Susan T.; Jayne, John T.

    1995-04-01

    The rate constant for electron attachment to SO3 is 3±1×10-9 cm3 s-1 at 300 K, measured in helium gas at pressures from 53 to 160 Pa (0.4 to 1.2 torr). The sole product of attachment is SO-3 under these conditions. The same rate constant and ionic product were obtained at 400 and 505 K. The measurements were carried out using a flowing-afterglow Langmuir-probe apparatus.